Synergy

Do you have multiple computers on your desk and need to control them all with a single keyboard and mouse - and don't have or don't want to use a KVM?

Then, Synergy is for you! See: http://synergy2.sourceforge.net/
Download and install on your various machines, making one the server and the rest clients and hey presto...

I have my iMac as the server and 2 PCs on either side as clients. I followed the 'Create a system level start up item' and put this:

/User/son_t/bin/synergys -f --config /Users/son_t/bin/synergy/synergy.conf as the run command for the server mode (example only shows the client setup).