Synergy+ lets you easily share a single mouse and keyboard between multiple computers with different operating systems, without special hardware.

iSynergyClient provides an independent client of the Synergy protocol for the iOS. In this implementation, middle and right mouse buttons can be assigned using Activator.

Text input is currently missing, but the hid-support project could be used for that.

More info on Synergy http://synergy-foss.org/