GrandPerspective is a small utility for Mac OS X that can draw two-dimensional views of disk usage within a file system. This can help you to manage your disk, as you can easily spot which files and folders take up the most space.
Version 0.9.13.1 of GrandPerspective has just been released. It fixes two bugs in the recently released Version 0.9.13 that on some systems caused crashes when scanning in folder contents.
The new release is available at http://sourceforge.net/project/showfiles.php?group_id=148156. More information about GrandPerspective can be found at the project's homepage: http://grandperspectiv.sourceforge.net/.