Finnish astrophotographer J-P Metsävainio has created some stunning 3D animations (more at his blog) of far-flung nebula. Phil Plait first pointed to them back in October. Today, there's a post on the Smithsonian Magazine's website about them.
100,000 Stars [SLInteractive3DVisualization] (Seems to run best on Chrome or Safari and a decent graphics card)
"Somewhere on the planet are ten-year-olds who, someday, will be the first people to set foot on Mars" 300 scientists and space-experts contributed to what's billed as "a realistic vision of the first Human Mission to Mars" -- Race to Mars. Discovery Channel Canada used Hollywood special effects, but for added realism rather than ray-guns and aliens. On the website, you can argue about whether they got it right. www.racetomars.ca
3D Starmaps by Winchell Chung. (I knew him for his game illustrations before I ever knew about his starmaps.) The site contains lots of information about how to make 2D/3D starmaps from standard star tables, a nice selection of pre-existing maps and one of the best listings of 3D starmap software around.
Ever have trouble visualizing how the solar system is put together, how the orbits work, how everything is positioned relative to everything else? This site helps you see how we think it all fits together.
3-D Maps of Nearby Space "The first detailed map of space within about 1,000 light years of Earth places the solar system in the middle of a large hole that pierces the plane of the galaxy...The new map, produced by University of California, Berkeley, and French astronomers, alters the reigning view of the solar neighborhood." (one view|another view|links to bigger images)