Synergy - Cross-platform software for sharing your mouse and keyboard between multiple computers
Input Director - Control multiple windows systems with one keyboard/mouse. Share a keyboard and mouse across multiple windows system.
Barrier - Barrier is a cross-platform software for sharing your mouse and keyboard between multiple computers...
Ultramon - UltraMon is a piece of software built to help with the management of multiple screens on the same computer system. Without software like this, taking full advantage of an expanded desktop space can be difficult.
DisplayFusion - DisplayFusion will make your multi-monitor life much easier.
ShareMouse - With its easy setup and high level of versatility, ShareMouse is a great tool if you're looking to use a single mouse and keyboard across multiple computers.