Newmark's Door

I especially like #6, where you exercise on a stationary bike and the hotel pays you for the power you generate.

(But there's something really wrong with the numbers. The article states that a Danish hotel gives you $36 of food for 15 minutes on the bike which generates "10 watt hours of electricity". I don't know about Denmark, but in the U.S. the retail cost of electricity averages about 11 cents per 1000 hours. The hotel seems to be price discriminating in favor of people who are willing to exercise.)