Google Sky

If you haven't tried Google Earth yet, you should. It's a free download from Google that you can get here. You can zoom around the globe, search addresses, and add layers like Road Names, Parks and Recreation, Dining and Lodging. Very nifty. Even if you don't want to find a specific address, it's still fun to pan around the world and zoom in on terrain.
With the newest version 4.2 they have included Google Sky that does the same thing as Earth, but in the heavens. Since I'm the astronomy buff of the family I naturally had to give this a spin (no pun intended). To get to Google Sky, open Google Earth and click on the View menu. Choose "Switch to Sky." The layers for Sky include Constellations, Hubble Showcase, and Backyard Astronomer. You can do searches on the sky for constellation names, stars, nebula, and galaxies…really just about any sky object. You can also search using the Messier and NGC catalogs numbers. If you zoom in far enough to an object you will see a picture of it, and a pretty good one at that.
Granted I wouldn't use this for my primary sky charting software. I like Stellarium. much better and it's a freebie as well. However, this is a neat feature to add to Google Earth. Google has also put together Google Moon and Google Mars. You will have to browse to the website for these tools. It's a fun thing to play with if you want to take a trip to space without leaving the comforts of Earth.