I already thought the free Google Earth program was one of the coolest programs out there. Sort of a “digital globe”, you can zoom from looking at the entire Earth right up to your house or favorite location, change viewing angles, and fly to other places. That alone can occupy me to no end, but there is so much more you can do with the program. I think a good side benefit of Google Earth—and I’ve remarked on this before—is that to some degree, I feel it helps promote interest in geography. As one goes about exploring places, it’s difficult not to appreciate their geographical relationships, and eventually one starts exploring other parts of the world, as well.
But now Google’s taken this a step further. In their newest version, they’ve added the ability to explore the sky as well. Complete with Hubble imagery and loads of astronomical tidbits, this is a great new feature and one I hope will stimulate interest in astronomy.
Below is a video demonstration Google has created. There has also been a significant amount of media coverage—see, for instance, articles in New Scientist, SPACE.com, PC World, or other media.
I should note that the astronomical view is displayed as one might see it from Earth—sort of on the inside of a dome, not unlike a planetarium view. You cannot travel out into space. For that, I strongly recommend the excellent, free, and easy-to-use Celestia (wp). It’s beautiful, has an elegant interface, and is quite powerful. Google Earth plays a rather different role, and both programs complement each other nicely. I strongly urge everyone to download and explore both!
Update: Scientific American has a nice article, as well.
Ancora Imparo 
You have to click between Earth and sky… I was hoping you could just keep scrolling the Earth, and when you cam to the edge…
Yes, that does make it a bit awkward. I hope (and expect) it will eventually have a more seamless transition. Still, I commend them for adding this feature—I think it really has the potential to stimulate interest in astronomy.