2nd
Spark let you customize and (re)define your Mac OS X shortcuts. It’s also let you control iTunes and system command like the brightness and sound control.
Until now I was using Keyboard Maestro to customize my keyboard shortcuts and control system command from my external PC keyboard.
Spark is simpler, powerfull and most of all free.
Note: Spark has small plugin called Plain Clip Plug that let you paste unformatted text. It’s very handy.