A GUI tool, KDirStat, shows the data both in table form and graphically. You can see really quickly where most of the space is used.
http://dl.dropbox.com/u/2896691/stack/KDirStat.png(Not a very good screenshot, but you get the idea. Right-click and "View Image" to see it in full-size.)
I'm not sure if this is exactly the KDE tool you didn't want, but I think it still should be mentioned in a question like this. It's good and many people probably don't know it - I only learned about it recently myself.