Lightweight Window Managers?

bcrowell asks: "We have an old Intel machine (166 Mhz pentium, 32 Mb), previously used only for playing Civilization, on which I've now got Mandrake running. The problem is, it doesn't seem possible to run KDE in this amount of memory. I've heard about Linux being a good way to run serious software gracefully on older hardware, but not having a GUI is pretty limiting, unless you just want a server. Has anyone used a more lightweight window manager that they could recommend? Are there ways of configuring X, KDE, or GNOME so as to cut down on the memory requirements?" Yes, a simple browse of Freshmeat will net you loads of answers, but I'm sure the submittor would appreciate some of your experiences with the numerous choices of WMs, out there.