Control multiple computers using keyboard/mouse attached to one computer(Win/Lin/Mac)

• Synergy (Freeware, Open Source, Cross-platform) is Free and Open Source Software that lets you easily share your mouse and keyboard between multiple computers, where each computer has its own display. No special hardware is required, just a network connection. Usage is as simple as moving the mouse off the edge of your screen. You can even share your clipboard.
  
  Synergy is supported on Windows, Mac OS X and Linux.
  
• Mouse Without Borders (Freeware /Windows) is a Windows application that lets you control multiple Windows systems using the keyboard/mouse attached to one computer. It allows to copy-paste files between computers, share clipboard.
  
• Input Director (Freeware / Windows) is a Windows application that lets you control multiple Windows systems using the keyboard/mouse attached to one computer. It is designed for folks who have two (or more) computers next to each other and find themselves regularly switching from one system to the other. With Input Director, you can share a single keyboard/mouse across a set of systems. You switch which system receives the input either by hotkey or by moving the cursor so that it transitions from one screen to the other (in a very similar fashion to a multi-monitor setup). The idea being that you can position the monitors from two or more systems in a row and use a shared keyboard/mouse to control all of them.
  
  Input Director also supports a "shared" clipboard, in which you can copy data onto the clipboard on one system, transition across to another and paste.
  
  Input Director requires Windows 2000 (Service Pack 4), Windows XP (Service Pack 2), Windows 2003, Windows Vista, Windows 2008 or Windows 7. The systems must be networked.
  
• Multiplicity ($$$ / Windows) lets you control multiple computers with a single keyboard and mouse.
  
  Features:
  • Clip and Paste - Share your clipboard contents among your master and slave computers, including images!
  • File and Directory Copying - Easily move files, or entire directories between computers! (Pro Version)
  • Hotkey Support - Multiplicity supports fast switching to the connected computers via configurable hotkeys and mouse buttons!
  • Fade/Darken Indicator - Multiplicity can fade or darken the non-focus computers, to further enhance navigation speed.
  • Onscreen Display - Multiplicity can be configured to display an onscreen indicator of your current location.
  • Locking - Support for locking your mouse to a specific desktop (configurable).
  • Security - Full password protection, and domain control internally.
  • Threshold Option - Full support for threshold control of mouse movement between machines.
  • Alternative Control Methods - Multiplicity supports various control methods, such as Jog Dials, and Spatial Controllers!
• Teleport (Freeware / Mac OS) lets you use a single mouse and keyboard to control several Macs. Simply reach an edge of your screen, and your mouse teleports to your nearby Mac, which also becomes controlled by your keyboard. The pasteboard can be synchronized, and you can even drag & drop files between your Macs.

[any ANONYMOUS forum user]

Have used synergy to control 6 screens, Windows and Linux, and although set up can be a bit of a pain it really is great once it works. Be sure you are sending the synergy signal via ethernet and not wireless though, as otherwise, people could potentially sniff out your key presses.