Input Director is a completely free Windows application that allows you to share a keyboard and mouse across multiple physical systems over a network connection.
This is extremely useful if you have a few separate PC’s and laptops in the same workspace, and don’t want the hassle of using multiple keyboards and mice, or a physical KVM switch to manage each system.
The configuration is extremely simple: install the application on each system that you would like keyboard and mouse shared over, set your main system as the Master, and then configure each secondary system as a Slave. As a plus, you can enable encryption between the Master and Slave systems for added privacy over the network.
This is my config at home, a PC with two monitors, as well as a laptop with another screen attached. Input Director virtually allows me to treat this setup as a single device with four screens attached:
For cross-platform keyboard and mouse over network sharing, see the Synergy+ project. Synergy+ allows you to share keyboard and mouse over network across Windows, Mac and Linux clients. I will do a write-up on Synergy+ soon.