If you ever wanted to know which directories are eating away all the hard disk space jdiskreport is the answer.It's one of the few java programs I know whose interface doesn't suck.It supposedly works on windows,OSX and Linux (I have tested it only on Linux).
Seeing is believing :-)
1)You can save a scan.
2)Order by no. of files in a directory or directory size.
4)You can navigate the directory structure by clicking on the pie chart.