Wow this is pretty cool. I don't live in SF nor am I a club-goer, but I assume the market for such people is pretty big.
How do you get your data? How trustworthy is it?
Yesterday, we and some friends walked around SF and counted at each bar & restaurant. We need help though so when you're out, tweet or DM us your venue, ratio, and how crowded it is. We'll be sure to tweet it.
So basically I can get you to advertise my club if I tweet a favorable ratio to you, right? :-)