Right?
Well, Ubuntu has this great tool for doing just that: specifically, when you're trying to find where all your hard disk space has gone. It's called the Disk Usage Analyzer, and if you poke around just a little bit, you'll find the magic feature: Scan Directory.
Scan a directory, or a filesystem, and you'll find it easy to trash or explore directories that are taking up space, and it does this very quickly.
