Damn. We have a winner! I'll play anyway . . . I'm a traditionalist when it comes to baseball. I love MLB, it's my favorite sport to follow, etc. But, I think this would be fun: Offensive Rover. The team that's batting gets to send a player out in the field, anywhere in fair territory, except starting on the pitcher's mound or between the pitcher and catcher. He's allowed to interfere with a fielder in any way, without physically holding him. Batter is most likely to hit a ground ball to short? Stand right in front of him, screen him, yell "Noonan" at him, whatever. Stand behind second base, to encourage batters to try and stretch every single into a double by screening the throw from the outfield. The Rover has to be any one of the 9 in the lineup, and if it's his turn to bat, somebody else can go out. It would be fun to watch a guy running all over the field, getting in the way and such. It would add a lively dimension to some otherwise dull moments. (I mean, it's always popular when we do it in softball . . .)
NASCAR used to be like that up until the mid 70's. The drivers would call up the local dealership where they were racing and get a car off the lot to race. Of course, their crew would make some safety modifications and add a shit ton more horsepower, but the cars you saw on the track was the same cars you saw on the road. You would get dozens of different "production" cars running around the track. The saying was "Race on Sunday, sell cars on Monday." At the first one or two Daytona races, they even had a convertible division.
Limo NASCAR. - Each team also must have a dunk sorority girl hanging out the roof window yelling "OH MAH GADS I'M IN A LIMOZEEEEENNNN" MMA - both fighters must do a large pile of cocaine before the fight. (or do they already do this?) I always liked George Carlins suggestion that baseball fields get randomly placed landmines in the outfield, and that there should be a gas fire on each side of center in basketball to encourage the REALLY fast break.
Televised, competitive armed (swords) skydiving. The version with female combatants could be done naked other than for the parachute. I'd imagine that some of the ladies would whistle all the way down; if you know what I mean.