Tap your foot while using the Tablet PC
I have a friend that’s for years dreamed of foot mice. Can you tell that he’s a drummer? 
There have been devices like this over the years, but most have not caught on for one reason or another. I imagine for most of us it would take a bit of getting used to. However, the lack of success hasn’t kept the innovation circle spinning. I see this morning that Gottabemobile is pointing to a post by Ken Hinckley which shows how he constructed a foot switch ideal for right toe tapping, if you will.
Makes me think, what about using the webcam to look for my right eye blinking as a right click. Now that would be a pain if you had a twitch 