Synergy is quite good if you can make it work reliably with your setup. When I used it with my Mac as the server and my PC as the client, I ran into a bunch of issues such as modifier keys getting (virtually) stuck. Then I switched it around and made my PC the server and my Mac the client and a different set of problems arose. Luckily, there is an active discussion group and it's open-source, so if you were really keen on making it work, you could.