I use WinDirStat, http://windirstat.info/, to see what file users have accumulated in their home drives.
“WinDirStat reads the whole directory tree once and then presents it in three useful views:
- The directory list, which resembles the tree view of the Windows Explorer but is sorted by file/subtree size,
- The treemap, which shows the whole contents of the directory tree straight away,
- The extension list, which serves as a legend and shows statistics about the file types. “
Excellent program, and free.