I don't know if it already exists but I just came up with it. It's 50 bucks to get in. You take every team in the league and try to guess (before the season starts of course) what their W-L record will be in January. The person who has the least amount of overages/negations, wins 50% of the pot. Second gets 30% and third gets 20%. Does it sound plausible or is that just not enough action?

It's a 5 month season, most people don't want to wait that long for a bet to settle.