Coincidently enough yesterday I was discussing with the kids if I could rig up remote flipper buttons on an exercise bike so I could play pinball and train at the same time. I do a fair bit of cycling and sitting on the trainer when the weather's bad is the most boring experience in the world.

Technically it would be easy, I'm not sure if the viewing angle and not being able to feel the machine would take all of the fun out of it though. You could extend the idea and have the pin powered by the bike as well so if you slacked off it would shut down