Spectrwm (previously known as scrotwm) is a small dynamic tiling window
manager for X11.  It tries to stay out of the way so that valuable screen
real estate can be used for much more important stuff.  It has sane
defaults and does not require one to learn a language to do any
configuration.  It was written by hackers for hackers and it strives to be
small, compact and fast.

It was largely inspired by xmonad and dwm.  Both are fine products but suffer
from things like: crazy-unportable-language-syndrome, silly defaults,
asymmetrical window layout, "how hard can it be?" and good old NIH.
Nevertheless dwm was a phenomenal resource and many good ideas and code was
borrowed from it.  On the other hand xmonad has great defaults, key bindings
and xinerama support but is crippled by not being written in C.