You can get a pretty interactive treemap of the linux filesytem using http://gdmap.sourceforge.net/

[screenshot] http://gdmap.sourceforge.net/img/gdmap-preview.png

You can also see a treemap of the kernel although it is static http://www.cs.umd.edu/hcil/millionvis/Treemap_Visualization_...

I use KDirStat http://kdirstat.sourceforge.net/

In addition to the standard 'du' command, which you can sort and munge with the standard unix stuff, Gnome has bundled the 'baobab' utility for the last few releases (so if you're on a relatively recent Gnome release, you probably already have it installed). It has an interactive "rings" view and a "treemap" view, which are both pretty nifty.

In Ubuntu the default "Disk Usage Analyser" (the projeect name is "Boabab") in Applications -> Accessories does this.

By default it's a ring chart but there's a menu to select treemap instead. The authors seem to believe that treemaps are good for comparing only size, but the ring chart shows hierarchy well too.

http://www.marzocca.net/linux/baobab/baobab-ringschart.html

http://www.marzocca.net/linux/baobab/baobab-treemaps.html

I use WinDirStat for Windows http://windirstat.sourceforge.net/

du -hs /home/* | sort -k 1,1

/edit typo

I've always stuck with du | xdu. Except for the primitive rendering it is rather reminiscent of webtreemap (or vice versa, i guess) -- click to dive down, top to go back up.

For Gnome, it's called baobab (in Applications -> Accessories -> Disk Usage Analyzer).