It looks like the folks at the University of Udine are working on making exergaming more interactive. They are using an accelerometer and a heart rate monitor to affect gameplay:
You can see how the game works here:
It looks like a simplistic version of breakout, which typically isn’t a very exciting game. What I would like to see is DDR with a heart rate monitor. The dance steps increase or decrease depending on customizable heart rates. Why hasn’t Konami done this?