From Bartels Media:
ShareMouse allows you to share one mouse and keyboard with multiple Windows and Mac computers. You just need to move the mouse pointer to the computer you wish to control. When you reach the border of the monitor, the mouse cursor magically jumps to the neighboring monitor and you can then control that computer. Any computer can be controlled with the mouse and keyboard of any other computer. Unlike a KVM switch, you don't need to press any button to switch between computers. All mouse and keyboard input is transmitted over your existing Ethernet or Wireless LAN network connection. No USB switch, KVM switch or any other hardware is required. ShareMouse also allows you to drag and drop files between multiple computers for easy file transfer. ShareMouse additionally shares the clipboard between multiple computers. Whatever you copy into the clipboard of one computer is available in the clipboard of any other computer.