Also check Baseline (shareware): it scans your volume, then saves the results, so that you can see later which folders are bigger, and which are smaller.

To paraphrase Heinlein, there ain't no such thing as freeware - it's either Free (open source) software, or it no-payment-yet-until-we-decide-otherwise-ware. Wish Arne & Marcus could change the categories so that "Licence" actually reflected licencing terms and not pricing (which is a totally different concept).

xcgr is absolutely right.
WhatSize is not freeware anymore.
The price is around $13.

Version 4.0 (aka "10.4") asks you to buy a license when you start it up. Sorry to see this isn't freeware anymore. Back to version 10.3.92 for me.

This works well, though I prefer the slick and intuitive graphical DiskInventoryX interface.

love it

I use it often, helps me find stuff that are taking up lots of space that I don't use anymore. Very helpful!

A different (more graphical) approach to this is "Grand Perspective" (http://osx.iusethis.com/app/grandperspective) and "Disk Inventory X" (http://osx.iusethis.com/app/diskinventoryx).

This seems to be identical in function to OmniDiskSweeper and almost identical in appearance as well.

quickly see what large files are clogging up your harddrive.