Several great astronomy pictures. http://www.astronomy.net/astroimages
NASA website with great planet information http://solarsystem.nasa.gov/index.cfm?Display=NoFlash
Thorough pages of all planets http://www.solarviews.com/eng/homepage.htm
A lot of information about the 8 planets. http://nineplanets.org/
National Geographic site with information about the planets, asteroids, and "Space Junk" http://science.nationalgeographic.com/science/space/solar-system
Distances between the Sun and planets http://www.idahoptv.org/ntti/nttilessons/lessons2000/lau4.html
Planet info. with several interesting pictures http://www.space.com/solarsystem/
Look at "fast facts" for each planet http://www.kidsastronomy.com/solar_system.htm
General information about Solar System http://starchild.gsfc.nasa.gov/docs/StarChild/solar_system_level1/solar_system.html
Information about Inner and Outer planets, comets, meteors, and more http://www.nineplanets.org/overview.html
Great site for kids...including what the planets are made of!!! http://coolcosmos.ipac.caltech.edu//cosmic_kids/AskKids/index.shtml
Another helpful site...including what the planets are made of! http://www.lessonplanspage.com/more/205mar.html
Astronomy Picture of the Day! http://antwrp.gsfc.nasa.gov/apod/astropix.html
Information for each group topic: MARS http://marsrovers.jpl.nasa.gov/home/index.html