What is the best key remapper tool?
great question... I've been looking for a tool that will allow me to emulate TouchCursor for Windows on the mac for a long time.  Tried Ukelele, DoubleCommand, and some others that I can't remember right now :)  KeyRemap4Macbook seemed to be closest to what I needed, but I could never get around to configuring it how I wanted it.  Your mileage may vary.

Check out this page that gives some of the aforementioned programs and start playing :)