WinDirStat can be downloaded for free from here.
WinDirStat is a visual drive space manager that uses treemaps to represent each file as a colored rectangle, allowing you to instantly visualize file distribution across an entire drive or folder. In addition, the file types are color coded and can be clicked to reveal file name and details with options to access via Windows Explorer, copy the path, or to delete the file. The concept is very similar to SequoiaView, however it provides additional folder tree access and an easier to use interface, as well as right-click integration via SendTo menu.
this isnt a program that you will use every day, but when you need it, its certainly one of the best tools for the job. First opinions are sometimes deceiving, and the colorful usage/distribution display at the bottom of the screen was a bit disconcerting at first. After a few minutes of playing (who reads help files?), I realized that what looks like pop-art is probably the most powerful feature of this gem of a program. After understanding what it meant and how it worked, I fell in love with this little gem. Anyone can make good use of WDS, but its especially useful for people who have others using their computer. Whether its parents with kids that are filling their hard drives with junk, or IT admins who need to monitor their users disk space.
It may not be as automated as you want but hey it is free!
JDiskreport is another great free tool that can be run from a MAC also – since it runs under JAVA. It has been valuable to me also when looking at what files/folders are taking up so much space on a system.