I use Keyboard LaunchPad, but I only use it to Pause/Play windows media player. I select a play list, and if the door bell or phone rings, a quick "ctrl+p" lets me pause things without the need try to find the player. I haven't done much else with it... yet.
I have the sudden urge to try to figure out what else it can do.
Anyways, you probally can't do this yet, but I would like to be able to pause/play Youtube. Like I said, the door bell and the phone are some of my worst hated enemies. To be able to "pause/play" websites like that would be a much welcome feature.