I can’t believe I still go back to this app, but I just can’t argue with simplicity. Have you ever wanted to know which files or folder are the elephants in your hard drive? Well if this is your case try SpaceMonger. This nifty utility will show you in scale your files and folder according to size on drive.
If you do find something better send me a comment and I’ll surely try it out.
Update: Thanks to @cyberllaco for letting me know that WhatSize has the same functionality for Mac users.