Well now I have heard everything: this iPhone app (which they say is available for use internationally), works like like this:
You download it, register and commit to a certain number of days per week in at particular gym. You also committ to paying/being docked a certain sum if you do not meet that committment. The money goes into a common pool and the members who meet their target of attending get paid. I have not downloaded it, so I can’t judge or endorse it, but you can check it out here:
Check it out here: http://www.gym-pact.com/
And I would LOVE to hear any feedback from those who have actually tried it out.