[bayes]

Betting exchanges.

"You mean I can bet on sporting events, and the people providing the infrastructure are don't mind me winning (because they get paid commission anyway)? And the commission is on my net winnings per market, so the transaction costs don't depend on how many bets I make? And I can name my own bid and offer prices, like on a stock exchange? And I can automatically place hundreds of bets per hour through a well-defined (and free) API? And all my winnings are tax free (under UK tax law)? Cool.