Awesome WM

Awesome Window Manager is a tiling window manager.
It's light, fast, and very practical. I'm personally using dwm, which is very similar, but with less fancy stuff, and more stable. Both of them do something that most other window managers fail to do: they manage windows! Seriously, ability to drag, minimize and maximize your windows around the screen isn't window managing :).
Anyway, here's how window managers for real men look like: