Connect multiple mice, keyboards + monitors to one computer?

In order to do what you are asking you will most likey need a server and the thingamajig your are talking about is called a KVM switch. But usually most people use a KVM switch for connecting a mouse keyboard and monitor to two or more computers. I have 3 PC's but just one mouse keyboard and monitor. I said server because most PC's lack the power to 2 or 3 people working on them at the same time plus you would need a video card that would support two monitors.