AutoHotkey Equivalent for OS X?
Check out Hammerspoon. It seems to be very fully featured and — like AutoHotkey — offers a programmatic way to do all sorts of OSX automation, in addition to key binding/remapping.

(It takes a plugin based approach. Karabiner, mentioned in an answer above, can be used as a plugin too allowing its functionality to be enhanced in all sorts of ways.)

http://www.hammerspoon.org/