Synergy is an open source Sourceforge project allowing users to share mouse an keybord between several computers (MAC OSX, Windows, Linux). Synergy is very powerfull it allows to configure which machine is at the top/left/right/bottom to an other one. It also allows to map keybord between MAC and PC.

Ok, very fine, but MAC OSX users prefer to click in order to configure stuff... Right look at this UI for synergy. It rocks!