Stellarium: Whether you're a long-time, hard-core astronomy buff, or are just a part-time stargazer, you'll find something in this astronomy program for you.
It displays whatever celestial objects you want, including stars, planets, nebulae, and constellations, and will display the sky in various grids and from different points of view.
Click on any object to get details about it. Celestial objects move across the sky; you can have them move in excruciatingly slow real-time, or else speed them up. Overall, this is a beautiful and visually arresting program. It will draw pictures of the constellations, label them, and even let you change whether you want to see the night sky in darkness, or with some ambient light.
Almost all instant messaging problems have one big problem: They're each an individual island, unable to communicate with one another. If you're an AIM user, for example, you won't be able to communicate with MSN members, and vice versa.
Pidgin solves the problem neatly. It's a simple universal messenger that lets you communicate with multiple IM networks from a single client. You'll be able to connect to AIM, Yahoo! Messenger, MSN, ICQ, and many others. Also useful is that you can also get access to plenty of free plug-ins, including ones that can store a history of your IMs, store notes about buddies, and other handy functions. You may have heard of this program under a different name; until recently it was called GAIM.