Imagine the Universe!
Produced by the High Energy Astrophysics Science Archive Research Center
(HEASARC) at the NASA Goddard Space Flight Center
http://imagine.gsfc.nasa.gov/

Mars VE, The Virtual Exploration Mission
Produced at NASA Ames Research Center
http://exploringspace.arc.nasa.gov/vecd.htm

Teacher's Guide to the 3-D Tour of the Solar System
Lunar and Planetary Institute
http://cass.jsc.nasa.gov/research/stereo_atlas/SS3D.HTM