SawFish was the default WindowManager for GNOME untill the 2.2 release. It was originally called Sawmill, but the name was changed to SawFish due to trademark reasons. It is an extensible WindowManager completely relying on a LISP-based scripting language -- all window decorations are configurable and all user-interface policy is controlled through the extension language.
Part of CategoryWindowManager
3 pages link to SawFish: