Ever since I learned about Martin Shubik’s “dollar auction” game from Howard Raiffa, the larcenous part of my soul has wondered whether there might be a way to implement it in real life without going to jail.
Answer: Yes.
It’s called “Swoopo.” It masquerades as an auction site, but each bidder is charged 75 cents for each bid, and a bid only pushes up the price of the item by 15 cents.
[At least, I don't think you can go to jail for this; it ought to be illegal, but I can't figure out what actual law it violates. The operators seem to be frank about the mechanics, so there's no misrepresentation and therefore no fraud in the legal sense. And I don't think it's technically "gambling," either. Open to correction on this point from those who know.]
H/t Megan McArdle, Kevin Drum