There are an unbelievable number of websites out there devoted to
Mars. Here are a few I found useful as starting-out points: 
<li> Mars is now available in Google Earth! Check out <a href="http://earth.google.com/mars/">http://earth.google.com/mars/</a>
<li> There is an excellent interactive map of Mars at "The Solar
System in Pictures - The Planet Mars" by Alwyn Botha:
<a href="http://www.the-planet-mars.com/map-of-mars/map-mars.html">http://www.the-planet-mars.com/map-of-mars/map-mars.html</a>
<li> If you need to find out what all that Latin means in Martian
place names, take a look at the USGS "Gazetteer of Planetary
Nomenclature", Appendix 5: Descriptor Terms 
<a href="http://planetarynames.wr.usgs.gov/append5.html">http://planetarynames.wr.usgs.gov/append5.html</a>
<li> There's a very nice series of articles about the Martian terrain,
written for students and teachers, by one of the scientists for the
Mars Global Surveyor team, at "Essays Written for the Planetary
Society Marslink Project" by Mike Caplinger,
<a href="http://www.msss.com/http/ps/intro.htm">http://www.msss.com/http/ps/intro.htm</a>
<li> The various missions and instruments all have their own
web-sites, often with their own "Image of the Day". They're all linked
at <a href="http://mars.jpl.nasa.gov/">http://mars.jpl.nasa.gov/</a> -
just find the mission you want and you'll be pointed to the home
page. The NASA Photojournal
<a
href="http://photojournal.jpl.nasa.gov/index.html">http://photojournal.jpl.nasa.gov/index.html</a>
is the easiest way to find images. 
<li> The MGS topographic map is available many places, but usually at
reduced resolution. If you want the whole thing, you can get it at
<a
href="http://ssed.gsfc.nasa.gov/tharsis/mercat.jpg">http://ssed.gsfc.nasa.gov/tharsis/mercat.jpg</a>,
but beware! it's enormous: 12000 x 7000 pixels. 
<li> Check out the "Phobos Arts and Crafts" page, where you get the
plan for an assemble-your-own Phobos: <a href="http://www.planetary.org/blog/article/00001358">http://www.planetary.org/blog/article/00001358</a>
<li> There's a discussion of the Mars Direct plan on the web at "Mars
Direct: Headquarters for the Mars Direct Manned Mars Mission"
<a href="http://www.nw.net/mars/">http://www.nw.net/mars/</a>, plus a
Scientific American article by Robert Zubrin in the March 2000 issue:
"The Mars Direct Plan"
<a href="http://www.sciam.com/article.cfm?articleID=00087E38-5B46-1C75-9B81809EC588EF21 ">http://www.sciam.com/article.cfm?articleID=00087E38-5B46-1C75-9B81809EC588EF21 </a>

Sources for images used:
<li> Background image: Image of the "grand canal" (Valles Marineris)
of Mars from "Pictures of Mars and its Satellites" in  "The Nine
Planets: A Multimedia Tour of the Solar System" by Bill Arnett  
<a href="http://seds.lpl.arizona.edu/nineplanets/nineplanets/pxmars.html ">http://seds.lpl.arizona.edu/nineplanets/nineplanets/pxmars.html </a>
<li> Missions to Mars: A complete list can be found at
<a
href="http://solarsystem.nasa.gov/missions/mars_missns/mars-mod.html">http://solarsystem.nasa.gov/missions/mars_missns/mars-mod.html</a>.
The pictures of the various missions come from this page or links
therein. 
<li> MOLA scans:  MOLA Press Release 20 November 1997 <a
href="http://mars.jpl.nasa.gov/mgs/sci/mola/data1/mola_press.html">http://mars.jpl.nasa.gov/mgs/sci/mola/data1/mola_press.html</a>
<li> MOC picture example: MOC narrow-angle image R22-01670 <a href="http://www.msss.com/moc_gallery/r22_s04/images/R22/R2201670.html">http://www.msss.com/moc_gallery/r22_s04/images/R22/R2201670.html</a>
<li> Mars/Earth comparison: from Mars Exploration Rover Mission:
Classroom, poster comparing Earth and Mars, 
<a href="http://marsrovers.jpl.nasa.gov/classroom/">http://marsrovers.jpl.nasa.gov/classroom/</a>
<li> Mars seasons: from Adler Planetarium <a href="http://www.adlerplanetarium.org/cyberspace/planets/mars/seasons.html">http://www.adlerplanetarium.org/cyberspace/planets/mars/seasons.html</a>
<li> Phobos: APOD 2008 April 10
<a href="http://antwrp.gsfc.nasa.gov/apod/ap080410.html">http://antwrp.gsfc.nasa.gov/apod/ap080410.html</a> and 2008 April 14 <a href="http://antwrp.gsfc.nasa.gov/apod/ap080414.html">http://antwrp.gsfc.nasa.gov/apod/ap080414.html</a>
<li> Moons from Spirit: NASA Planetary Photojournal <a href="http://photojournal.jpl.nasa.gov/catalog/PIA06340">http://photojournal.jpl.nasa.gov/catalog/PIA06340</a>
<li> Martian atmosphere: from "SpaceKids: Mystery of Mars" 
<a href="http://www.spacekids.com/spacenews/mystery_mars_991201.html">http://www.spacekids.com/spacenews/mystery_mars_991201.html</a>
<li> Structure of Martian atmosphere: from Jim Brau: Astronomy 121 
<a href="http://physics.uoregon.edu/~jimbrau/astr121/Notes/Exam2rev.html">http://physics.uoregon.edu/~jimbrau/astr121/Notes/Exam2rev.html</a>
<li> Clouds: Mars Global Surveyor release MOC2-118 <a href="http://www.msss.com/mars_images/moc/4_11_99_tharsis/">http://www.msss.com/mars_images/moc/4_11_99_tharsis/</a>
<li> Dust storm: Planet-wide dust storm, using observations from the
orbiting Mars Global Surveyor. From "Astronomy Picture of the Day",
2001 July 27 <a href="http://antwrp.gsfc.nasa.gov/apod/ap010727.html ">http://antwrp.gsfc.nasa.gov/apod/ap010727.html </a>
<li> Dust storms on Mars and Earth: from "Mars Global Surveyor: Recent Mars and Earth Dust Storms Compared", MGS MOC Release No. MOC2-249, 12 September 2000 
<a href="http://mars.jpl.nasa.gov/mgs/msss/camera/images/9_12_00_dust_storm/  ">http://mars.jpl.nasa.gov/mgs/msss/camera/images/9_12_00_dust_storm/  </a>
<li> Dust devil: <a href="http://photojournal.jpl.nasa.gov/catalog/PIA09260">http://photojournal.jpl.nasa.gov/catalog/PIA09260</a>
<li> Sky panorama: Astronomy Picture of the Day 2006 October 17 <a href="http://antwrp.gsfc.nasa.gov/apod/ap061017.html">http://antwrp.gsfc.nasa.gov/apod/ap061017.html</a>
<li> Mars temperatures: NASA Planetary Photojournal <a href="http://photojournal.jpl.nasa.gov/catalog/PIA02014">http://photojournal.jpl.nasa.gov/catalog/PIA02014</a>
<li> Water pressure-temperature diagram: from Mars Polar Lander: Volatiles, 
<a href="http://mars.jpl.nasa.gov/msp98/mvacs/overview/volatiles.html">http://mars.jpl.nasa.gov/msp98/mvacs/overview/volatiles.html</a>
<li> Magnetism: from MGS MAG/ER Publications <a href="http://mgs-mager.gsfc.nasa.gov/publications/pnas_102_42_connerney/">http://mgs-mager.gsfc.nasa.gov/publications/pnas_102_42_connerney/</a>
<li> Mariner image: NASA Planetary Photojournal <a href="http://photojournal.jpl.nasa.gov/catalog/PIA02979">http://photojournal.jpl.nasa.gov/catalog/PIA02979</a>
<li> Valles Marineris hemisphere: mosaic of Viking images, from
<a
href="http://seds.lpl.arizona.edu/nineplanets/nineplanets/mars.html">http://seds.lpl.arizona.edu/nineplanets/nineplanets/mars.html</a>
Dust storm in Hellas: Science@NASA 9 July 2003 <a
href="http://science.nasa.gov/headlines/y2003/09jul_marsdust.htm">http://science.nasa.gov/headlines/y2003/09jul_marsdust.htm</a> 
<li> Topographic image of Mars: taken by the Mars Global
Surveyor. From the NASA Planetary Photojournal 
<a href="http://photojournal.jpl.nasa.gov/targetFamily/Mars">http://photojournal.jpl.nasa.gov/targetFamily/Mars</a>, image PIA02031: Maps of Mars Global Topography.
<li> Landing sites: <a href="http://jpl.nasa.gov/news/phoenix/images-all.php?fileID=5296">http://jpl.nasa.gov/news/phoenix/images-all.php?fileID=5296</a>
<li> Two hemispheres: from "Seeing the martian crustal dichotomy" by
Mike Caplinger <a
href="http://www.msss.com/http/ps/di.html">http://www.msss.com/http/ps/di.html</a> 
<li> Channels in Hellas: MOC narrow-angle image M20-00092 <a href="http://www.msss.com/moc_gallery/m19_m23/images/M20/M2000092.html">http://www.msss.com/moc_gallery/m19_m23/images/M20/M2000092.html</a>
<li> Dunes in Hellas: MOC Release MOC2-537, 7 November 2003 <a href="http://www.msss.com/mars_images/moc/2003/11/07/">http://www.msss.com/mars_images/moc/2003/11/07/</a>
<li> Image of the crater Yuty: NASA/Viking Orbiter image 3A07. Colour
version from <a href="http://www.nirgal.net/crater.html">http://www.nirgal.net/crater.html</a>
<li> Craters: from Mars Odyssey Mission THEMIS: Topic Gallery: Craters 
<li> Bacolor Crater: from Mars Odyssey Mission THEMIS: Feature image
<a href="http://themis.asu.edu/features/bacolorcrater">http://themis.asu.edu/features/bacolorcrater</a>
<li> Water map of Mars: from Astronomy Picture of the Day, 2004 September 4, 
<a href="http://antwrp.gsfc.nasa.gov/apod/ap040904.html">http://antwrp.gsfc.nasa.gov/apod/ap040904.html</a>
<li> Network of streams: from "Views of the Solar System" by Calvin Hamilton, 
<a href="http://www.solarviews.com/cap/mars/network.htm">http://www.solarviews.com/cap/mars/network.htm</a>
<li> Islands: from "Views of the Solar System" by Calvin Hamilton, <a href="http://www.solarviews.com/cap/mars/islands.htm">http://www.solarviews.com/cap/mars/islands.htm</a>
<li> Tharsis topography: from Tharsis and the Early Climate of Mars <a
href="http://ssed.gsfc.nasa.gov/tharsis/tharsis_paper.html">http://ssed.gsfc.nasa.gov/tharsis/tharsis_paper.html</a>
<li> Viking view of Tharsis: from NASA Planetary Photojournal <a href="http://photojournal.jpl.nasa.gov/catalog/PIA02987">http://photojournal.jpl.nasa.gov/catalog/PIA02987</a>
<li> Olympus Mons:  from "Views of the Solar System" by Calvin
Hamilton: Martian Volcanoes
<a href="http://www.solarviews.com/eng/marsvolc.htm">http://www.solarviews.com/eng/marsvolc.htm</a>
<li> 3D view of Olympus Mons: from NASA's "Mars Exploration Program:
Olympus Mons"
<a href="http://mars.jpl.nasa.gov/mep/science/olympus_mons.html">http://mars.jpl.nasa.gov/mep/science/olympus_mons.html</a>
<li> Crater counting in calderas: from Neukum et al. 2004, Nature 432,
971, news article from PSRD: Recent activity on Mars - Fire and Ice by
Linda Martel, <a href="http://www.psrd.hawaii.edu/Jan05/MarsRecently.html">http://www.psrd.hawaii.edu/Jan05/MarsRecently.html</a>
<li> Valles Marineris: full-globe view from "Mars Exploration" <a href="http://mars.jpl.nasa.gov/index.html">http://mars.jpl.nasa.gov/index.html</a>
<li> Labelled Valles Marineris map and rendering: from <a href="http://ltpwww.gsfc.nasa.gov/tharsis/vm_renders.html">http://ltpwww.gsfc.nasa.gov/tharsis/vm_renders.html</a>
<li> Coprates Chasma: Mars Express image <a href="http://esamultimedia.esa.int/images/marsexpress/191-170505-0449-6-nd-01-Coprates_H.jpg">http://esamultimedia.esa.int/images/marsexpress/191-170505-0449-6-nd-01-Coprates_H.jpg</a>
<li> Flight Through Mariner Valley: from NASA Planetary Photojournal
<a href="http://photojournal.jpl.nasa.gov/catalog/PIA02892">http://photojournal.jpl.nasa.gov/catalog/PIA02892</a>
<li> NASA Spacecraft Photographs Avalanches on Mars: <a href="http://www.nasa.gov/mission_pages/MRO/news/mro-20080303.html">http://www.nasa.gov/mission_pages/MRO/news/mro-20080303.html</a>
<li> Phoenix: from Wikipedia
<a
href="http://en.wikipedia.org/wiki/Phoenix_(spacecraft)">http://en.wikipedia.org/wiki/Phoenix_(spacecraft)</a>
and APOD 2008 November 12  <a
href="http://antwrp.gsfc.nasa.gov/apod/ap081112.html">http://antwrp.gsfc.nasa.gov/apod/ap081112.html</a>
<li> Possible ancient shorelines: from Head et al. 1999, Science 286,
2134; figures available at 
<a href="http://ssed.gsfc.nasa.gov/tharsis/ocean_paper.html">http://ssed.gsfc.nasa.gov/tharsis/ocean_paper.html</a>
<li> Proposed shorelines on the Cydonia plains: from Clifford & Parker
2001, Icarus 154, 40 
<li> Vastitas Borealis Formation: from "Ancient Floodwaters and Seas
on Mars" by Linda Martel,
<a href="http://www.psrd.hawaii.edu/July03/MartianSea.html">http://www.psrd.hawaii.edu/July03/MartianSea.html</a>
<li> Layers in Schiaperelli: Mars Global Surveyor release MOC2-403 <a href="http://www.msss.com/mars_images/moc/2003/06/26/">http://www.msss.com/mars_images/moc/2003/06/26/</a>
<li> Layers in Holden Crater: Mars Global Surveyor release MOC2-262 
<a href="http://www.msss.com/mars_images/moc/dec00_seds/holden/index.html">http://www.msss.com/mars_images/moc/dec00_seds/holden/index.html</a>
<li> Delta in Holden Crater: Mars Global Surveyor release MOC2-543 <a href="http://www.msss.com/mars_images/moc/2003/11/13/">http://www.msss.com/mars_images/moc/2003/11/13/</a>
<li> New gully deposits: from NASA Mission News 6 December 2006 
<a href="http://www.nasa.gov/mission_pages/mars/news/mgs-20061206.html">http://www.nasa.gov/mission_pages/mars/news/mgs-20061206.html</a>
<li> Images from Spirit and Opportunity rovers: all images from NASA
Planetary Photojournal: Mars, 
<a href="http://photojournal.jpl.nasa.gov/targetFamily/Mars">http://photojournal.jpl.nasa.gov/targetFamily/Mars</a>
<li> South polar ice cap: from Views of the Solar System: South Polar Cap 
<a href="http://www.solarviews.com/cap/mars/southpol.htm ">http://www.solarviews.com/cap/mars/southpol.htm </a>
<li> Layers at the pole: from Views of the Solar System: Polar
Laminated Terrain 
<a href="http://www.solarviews.com/cap/mars/layers.htm">http://www.solarviews.com/cap/mars/layers.htm</a>
<li> Water at the south pole: ESA News 15 March 2007 <a href="http://www.esa.int/SPECIALS/Mars_Express/SEMSWJQ08ZE_0.html">http://www.esa.int/SPECIALS/Mars_Express/SEMSWJQ08ZE_0.html</a>
<li> Ages of Martian surfaces: from Malin Space Science Systems:
Determining the age of surfaces on Mars 
<a href="http://www.msss.com/http/ps/age2.html">http://www.msss.com/http/ps/age2.html</a>
<li> Location of channels: from Malin Space Science Systems: Mars
Channels and Valleys
<a href="http://www.msss.com/http/ps/channels/channels.html">http://www.msss.com/http/ps/channels/channels.html</a>
<li> Ocean on Mars: from NASA Astrobiology Institute
<a href="http://nai.nasa.gov/news_stories/news_detail.cfm?article=old/marshypothesis.htm">http://nai.nasa.gov/news_stories/news_detail.cfm?article=old/marshypothesis.htm</a>
<li> Carbon dioxide outburst: from "Water On Mars? Who are they trying
to Kid?" by Nick Hoffman 
<a href="http://www.earthsci.unimelb.edu.au/mars/Outburst.html">http://www.earthsci.unimelb.edu.au/mars/Outburst.html</a>
<li> Ocean on Mars: photo by Radim Spitzer <a href="http://www.fotocommunity.com/pc/pc/display/5286151">http://www.fotocommunity.com/pc/pc/display/5286151</a>
<li> Mars obliquity variations: from Laskar et al., Paleoclimats
martien,
<a href="http://www.obspm.fr/actual/nouvelle/oct02/mars.en.shtml">http://www.obspm.fr/actual/nouvelle/oct02/mars.en.shtml</a>