Open Look Virtual
Window Manager.
A patched version of olwm, the original window manager distributed with OpenWindows.
Its main feature is virtual desktops (whence the name); another benefit is its lack of support for, and hence, lack of dependency on, Tooltalk, the OpenWindows desktop integration facility.
10 years from its creation, olvwm isn't likely to be one's favourite window manager: the Open Look GUI, never popular, is all but obsolete, and these days, window managers offer many more features and customizability.