If you're looking for a really cool night sky or astronomy program, I downloaded Stellarium the other day from http://www.stellarium.org/. I'm impressed. Here's how they describe their program: Stellarium is planetarium software that shows exactly what you see when you look up at the stars. It's easy to use, and free.

You can also zoom in on selected objects to see what they look like through binoculars or a telescope. I like the feature of speeding the time up, and/or reversing it. It's a little weird to figure out how to use it, most of the functions are controlled by the keyboard, but you won't know that until you look at the manual. You have to download the user's manual or visit the page on the web site.