Here's an Idea....

From Idea a Day, the notion of a mouse that helps manage your time at the PC, to avoid things like... blood clots:

Develop a mouse for computers that has a timer on it which the user can set for the maxium [sic] period of time they would like to be sitting at the computer. Once this time lapses the mouse will begin squeaking like a rodent. If the user persists, the squeaks will turn into mutterings of 'computer geek' to warn the user that they are in danger of becoming an anorak.

Sounds like a good idea, but, how do you become an anorak?