Just tried the latest version of Google Earth. New feature: Toggle between Earth and deep space. They have made a "sky" to look at from any point on earth, made up from pics taken by the Hubbles Space Telescope. I can say, if you're interested in space, stars, nebulas, black holes and all sorts of weird stuff out there, this new feature ROCKS!

Needless to say, you can zoom, see the constellations, mark "sites" of interest and pretty much all the usual stuff you can do "on Earth" except the lack of gas stations and cheap motels out in space is shocking :P