Ever had more than one machine on your desktop but wanted only one Keyboard and mouse to control them both? In the past I have used hardware KVM switches like the one below to physically plug the keyboard and mouse into both machines.
Recently I discovered a software KVM called Synergy. Synergy means you don't need a hardware KVM like the one above as it uses the network instead.
Here is my setup at the moment. I have a desktop PC with a Keyboard and mouse and screen plugged into it. I also have a laptop.
Both machines are plugged into the network.
Synergy can be installed on the PC as a KVM 'server', making its keyboard and mouse available on the network.
The Laptop runs the Synergy client application and connects to the PC over the network. Once the connection is establish I can use the mouse and keyboard as if it was a standard dual screen setup. I drag my mouse to the right and it appears on the laptop, I drag it left and its back to the PC.
There is an initial configuration of Synergy that can be a bit confusing. You essentially have to tell it where your screens in relation to each other and map the usable space. Below is how I've got mine setup.
In the screens you add the network names of the machines you want to use. The links here define a route right from the PC into Laptop territory and a route left to get you back to the PC.
Now I can seamlessly switch between the machines that are in front of me, they even share a clipboard so you can copy and paste from one to another. The only issues I've come across is that it locks you out from UAC elevated applications and it won't work on ctrl-alt-del login screens, for obvious reasons.
Just to see if I could I tried the following setup just for fun.
Sure enough you can move your mouse left and right between all these machines and use them, it even works with the PC that has two monitors.
Synergy is open source and released under the GNU Public License (GPL) and is available here.