I really wish these products existed for more than the PS2, or that I'd known of them before now. These are awesome: http://www.thinkgeek.com/clearance/toysgoodies/98ed/Basically it's an interruption of your PS2 controller, and it will only allow signals to the PS2 when you are exercising. How cool is that?!Personally I am starting a new workout, muchly involving gaming. That way I hope to keep interested. These are tempting, but with such a high price tag I need to think about it.
Actually stuff like that does exist for more than just the PS2. The Gamebike, for example, works with the PS2, Gamecube, and XBOX. More expensive though, of course.