FVWM

From Grokdoc

FVWM is a light window manager, with a long and rich history. It has an extensive set of man pages, a well organized web site, several mailing lists, and an IRC room that are all excellent sources of information. See the FVWM web site for more.

For users that don't want to spend a lot of time learning the configuration file format, there is an FVWM-Themes project that allows for the quick installation and use of new themes with little to no actual work. Check it out at sourceforge.