how to send keystroke from one computer to another with arduino

I would like to be able to enter a keystroke on my home computer and send that keystroke over the internet to a second computer connected to an Arduino with which I’m communicating via Skype, IM, etc. For example, press “>” on my home computer and have the Arduino at work turn the lights up and “<” to turn the lights down. All of the searches (here & Google) I’ve tried have the opposite-- assuming that the Arduino is connected to the computer on which the keystroke is made.
Ideas or links to a forum discussion or tutorial?