Anyone know of a good replacement for Synergy2 that is cross platform and open source? I've been looking around since I upgraded to Win7 which Synergy2 doesn't play well with - which doesn't surprise me since it doesn't look like there has been active development since 2006.
You're looking for Synergy which is in active development.
You could try Input Director - http://www.inputdirector.com/
However, it only supports Windows.