SkyView
A "virtual" observatory dynamically generating images of the sky in different wavelength regimes from a static image database, intended as a quick look facility to see the heavens.
URL: http://skyview.gsfc.nasa.gov/
Hands On Universe
Enables students to investigate the Universe while applying tools and concepts from science, math, and technology.
URL: http://hou.lbl.gov/
Space Place
Make a pop rocket that really works, solve a riddle, and dive beneath the surface of Mars. Do these things and more, and learn about space and astronomy at the same time.
URL: http://spaceplace.jpl.nasa.gov/
Munich Astro Archive
Data on astronomical objects - you do not need special knowledge to use the information which is collected here.
URL: http://www.maa.mhn.de/
