A game I've had in the back of my head for some time is a baseball RPG. It's got a great structural similarity to RPGs - team play, season as campaign, individual heroics within the context of a group, rivalries and friendships both within the team and with other teams, tactics, strategy, risk, and reward. It's also awesome fun!
I want to do this using the StarPool resolution system - used in Blood Games II, OHMAS, and Outremer - because it's easy to deal with contested actions by subtracting successes from each other, or with uncontested actions by changing the TN. I would also set up a Company Resource allocation bit like in OHMAS and Outremer, to buy Free Agents, maintain and expand the park, and pay for other players. Income would be based on market size and modified by success. There would be a troupe aspect - the players would be both owners as well as players.
Most games wouldn't be played out - I mean there are 162 games in the season, plus playoffs and World Series. A Notice system might make sense as well - as in the In Harm's Way series of games - for appropriately rewarding important successes and failures.