i3 - A dynamic tiling window manager designed for X11, inspired by wmii, and written in C.
dwm - dwm is a dynamic window manager for X. It manages windows in tiled, monocle and floating layouts. All of the layouts can be applied dynamically, optimising the environment for the application in use and the task performed.
Openbox - Openbox is a highly configurable, next generation window manager with extensive standards support.
Xmonad - xmonad is a dynamically tiling X11 window manager that is written and configured in Haskell.
Sawfish - Sawfish is an extensible window manager using a Lisp-based scripting language.
bspwm - A tiling window manager based on binary space partitioning