Enlightenment. Man I haven't used that windows manager in ages. Back in the day when the only developer for the WM was rasterman. I pretty much stopped using it when he stopped developing it.
Have you looked into
BlackBox not as nice as Enlightenment, but it is very light weight. I was very skeptical about this WM when it first came out but it has proven itself. Over the years is has built a large community as well as widgets for the BB.
=X=