aw, hell. it's true. there's very little that HASN'T been done.
http://www.motorfun.biz/bic-stroke.html
yes, the bicycle-powered fucking machine exists, and it's simpler than I envisioned, due to a less solid design. Rather than modifying a wheel strong enough to support a human, it replaces the wheel entirely with a set of discs and joins them with a moveable pin which holds the piston. pretty simple. I dismissed the idea because it seems flimsy and likely to fall apart, but then, we're not exactly talking 100 pounds of force per stroke.
http://www.motorfun.biz/bic-stroke.html