I came across a pretty cool free program the other day whilst out in my internet wanderings, and I thought you all might benefit from it. Often I'll be working on cleaning out a computer that's been used and abused for quite some time, and disk space is running low. A lot of the time, this is a real pain to fix. You have to look through all sorts of files to determine where the big ones are--hopefully big ones that you no longer need. Enter WinDirStat. (Check out the post on it over here.)
In a nutshell, this program scans your computer and then gives you a visual representation of the files you have stored on it. All files of a certain type will be one color, and they are represented by squares of various sizes. This makes it incredibly easy to spot big files, find out what they are, and then delete them. Convenient, pretty fast, and free.
A winning combination.