i'll throw in another recommendation for xfce(4), i just started using this to escape from the *box obsession because i just needed a change, and it's a great window manager (desktop environment?), it's nice and fast, i'd describe it as the offspring of a *box and trimmed down gnome, the only thing i don't like about it is it's pretty much all gui configured, i like the box 'hack method' where you have to do everything from config files, it makes me feel special and smart :]
and for something that i don't think has been mentioned in this thread..or maybe it has, Pekwm is great for a box style lightweight wm, it's very configurable and has some awesome themes, its only drawback is its "harbour" the fluxbox slit clone that has about a third of the functionality, it's a work in progress, and as a whole not too shabby
here's another thread on the same topic....
http://forums.gentoo.org/viewtopic.php? ... ow+manager