These aren't games that I'd necessarily buy, and in some cases, there're pretty sound fiscal reasons why these games don't yet exist. It's just that I find their absence curious. I mean, I can't be the only person who's thought of these:
Harlem Globetrotters
Now this may work better as an unlockable mode in the NBA series, ie unlock a new Globetrotter with every championship, and when you've unlocked enough Globetrotters to make a team, you can play exhibition games in Globetrotter mode.
Or maybe there's a decent standalone game to be found there.
Stickball
Why doesn't this exist? In fact, why doesn't Spalding license/advergame a whole suite of pink ball/"spaldeen" games, stickball, stoop ball, handball, etc. Here's the rules:
http://www.spaldeen.com/gamesrules.html
College/Olympic wrestling
Kickball
And dodgeball, for that matter.
Feel free to add more...