Synergy: One keyboard (and mouse) to rule them all

For a well written, commercial quality "what is this about", read here: http://www.stardock.com/products/multiplicity/

If you're sold on the idea, download here: http://synergy2.sourceforge.net/index.html

If you're using ubuntu, install it like this: http://philisoft.com/blog/install-latest-synergy-on-ubuntu/

To configure, reference here: http://www.linux.com/article.pl?sid=06/05/25/1439237