GymPact: Work out, or it'll cost ya...

I love products that users inflict on themselves in order to change their behavior for the better (remember the cash-shredding alarm clock?), and this one definitely counts.  GymPact is a system that pays you to go to the gym - and charges you when you don't.  It's pretty simple: you commit to a certain workout schedule, pay money when you don't go, and that same money gets paid out to people who do keep their schedule. The app seems to have clever enforcement techniques, like making sure you check in to the gym by actually being at its location as determined by your phone. Hey, if it makes people work out more, I'm all for it!