ThinkGeek have this Phantom Keystroker which does nothing but makes random mouse movements and type out odd garbage text and phrases for your unsuspecting victim. Switches on the side of this gizmo allow you to chose between keyboard garbage typing, caps lock-toggle and annoying mouse movements or all three. There’s even an adjustment dial that sets a duration between annoying events. Sounds like a fun time. Slap this onto your cube-mate’s unsuspecting computer (PC and Mac supported though the Mac may not support every function) and sit back and wait for that call from HR and the inevitable handshake for tampering with company IT resources.