Wikisky: It's like Google Earth, only for everywhere else. Wikisky is a free, online skymap to guide you through the heavens. You can search for specific objects or click-and-drag your way around the universe. It also shows the constellations, so you can look for your favorites. What can I say? This is cool.

Position your mouse over one of the millions of objects it knows about and you get a pop-up box identifying it. Click on it and you get a lot more info, including images, distance, location, and even links to related articles. Whether you're a serious sky buff or you just want to be able to find Polaris, the North Star, this is a pretty awesome tool.