Have caps lock mapped to quick escape and control (i.e. tap for escape and hold down for control). Somewhat related, left-control is mapped to Hyper. This post was an inspiration: http://stevelosh.com/blog/2012/10/a-modern-space-cadet/#happ...

Combined with ShiftIt, I can approximate a primitive keyboard-controlled tiling window manager on the Mac: https://github.com/fikovnik/ShiftIt