I don't think this is necessary for basketball. Having played quite a bit of pickup basketball in SF (and other cities), if you want to play basketball just go to the court with a ball. If there is nobody there, you just shoot around until enough people are there for a game to start. However more often than not on a weekend or other prime times there are already people there and you just join a random group and get in line.
It would be good to get people of similar skill to play together. I hate playing with the total scrubs and I hate playing with the ex Varsity athletes. Also it would be nice to meet someone else who has to use contrived situations to make friends.
Tennis was an example of why you wanted to reach out to people around you. Expanding on that thought, we believe there is tremendous value is connecting with the people around us. Right from asking question, advice, recommendations and borrowing stuff to finding people who live/work around us and share a similar interest - like jamming or something else.
That's precisely the idea behind a friend's startup! http://tennishub.com/ (TennisHub)