ShareKM!

Mouse Without Borders allows you to reach across your PC's as if they were part of one single desktop. Using Mouse Without Borders you can move your mouse between the 3 or more screens, even though one of them is attached to a different PC from the other two. You can also move files between the 2 computers simply by dragging them from one desktop to another. In fact you can control up to four computers from a single mouse and keyboard with no extra hardware needed – it’s all software magic, developed by Truong Do who by day is a developer for Microsoft Dynamics. The software is easy to setup and in addition to enabling drag and drop of files, you can lock or log in to all PCs from one PC, and as a whimsical bonus is it allows you to customize your Windows logo screen with the daily image from Bing or a local collection of pictures. »

spacedesk is a windows network display monitor software that expands the Windows desktop computer screen to other computers over the local area network.

Mouse and Keyboard Sharing to control a Windows or Mac PC with the mouse and keyboard of any other PC.

Really smooth and easy to use mouse and keyboard sharing between multiple machines. Set up the location of other shared desktops and simply arrange them just like the standard multi-monitor setup screen were all used to.

SynergyKM is a GUI wrapper around the synergy command line tool that lets you easily share a single mouse and keyboard between multiple computers with different operating systems without special hardware.