Window manager for the
X window system developed by
Brad Hughes,
et. al.
Blackbox is small and fast (that being its primary goal). As a result it's generally regarded as not being as aesthetically pleasing as Window Maker, Enlightenment, etc., but in fact it does look quite good. Blackbox is theme-able as well (http://bb.themes.org), like all other cool window managers.
http://blackbox.alug.org