The Long Bets Foundation tracks Long Bets on "societally or scientifically important" topics. For example, Bet #1 is a wager of $20,000 between Mitch Kapor and Ray Kurzweil debating whether a machine will pass the Turing test by 2029.
I'll be 58, but boy won't it be exciting. It's $50 to make a prediction, $200 to make a bet. Winnings go to your designated charity, and it's all administered by the The Farsight Fund portfolio at Capital Research.