The 4-Port KVM Switch a neat little unit for where you want to use more than one PC with a single monitor, keyboard and mouse.
The unit is quite small and unobtrusive, and comes with all the cables you need. Connection is a synch, just follow your nose, I didn't even look at the instructions. And it works, like a gem, simple switching between PC's with the flick of a button.
I only have 2 PC's running through the switch but it can take up to 4. As an added bonus it doesn't require an additional power source to run, picking up it's power from the keyboard input.