Synergy lets you seamlessly control multiple computers, even ones running different operating systems, using the same mouse and keyboard.
Ranked in these QuestionsQuestion Ranking
Pro Multiple OS support
Can share mouse, keyboard, and clipboard between Windows, Mac OSX, Linux, with unofficial clients for Android and iOS.
Pro Copies clipboard across computers
It's possible to copy multimedia content across computers, such as images, tables, html, text, and more.
Pro Open Source
You can add features to the software yourself if needed.
Pro Drag and Drop of files between MacOS and Windows
Synergy can be used for file transfer using intuitive drag and drop interface.
Pro Has SSL authentication/encryption
Especially since the shared keyboard data may contain passwords, and the application can "control your computer" (as the MacOS X permissions dialog puts it) it is important to ensure that the connection between computers is secured so that even if you are using it on an open WiFi hotspot, others cannot see the data being sent, nor can they inject data into the connection.
Pro Low latency
Low latency can be ensured by directly connecting computers via crossover cable.
Pro Clients for jailbroken iOS and modded Android devices
It's possible to use computer's keyboard and mouse with a jailbroken tablet or phone.
Con Requires a host computer
Only one computer can act as a host at a time, and the mouse/keyboard sharing is one way. So if you have computer at home, and a computer at work and you want to link your laptop to different computers depending on where you are, you need to change the host settings for each location.
Con Paid binaries
Despite being open source, Synergy charges for builds of their binaries.
Cost of $19 for Synergy Basic, or $29 for Synergy Pro.
Older versions of the binaries are available for free, and the source code can be downloaded and compiled manually.
Con (OSX) Scrolling in Chrome etc on client machines is very jittery
While scrolling on the 'server' is normal.
Con Random freezes when moving your mouse to the client side
Sometimes the mouse and keyboard freeze for 10-30secs randomly, and won't stop until you restart the program.