WorldWide Telescope

In competition with Google Sky, this application allows you to take a look at the stars through multiple images of constellations and what not.

Pretty much think Virtual Earth, but for the sky and you basically have it figured out. It's actually a pretty interface, and seems to work decently as long as you fulfill the Windows requirements. Bravo by Microsoft Research for this product. I'm not so sure if this product would make me cry though.

Despite Scoble push, I did find that not having any screenshots or even videos for those that are on non-Windows operating systems slightly disappointing. Outside of that, the interface itself is worthwhile as a tool to teach astronomy. Take a look if you find some time.