Control 2 PCs using one keyboard and mouse with the free version of Multiplicity 2.0 and up to 9 PCs with the pay version. It’s more versatile, more convenient, and less expensive than a KVM or KM ...

If you run multiple computers and monitors in close proximity to each other, Stardock's Multiplicity 2.0 (free and $40 premium editions) is a cheap and effective alternative to a physical KM switch.