This is just genuis:

Stop me if this sounds familiar. You venture out with your crew on a Friday night to a downtown hotspot only to find that the guy-girl ratio is totally out of whack. Instant buzz kill. Enter your new wing man Assisted Serendipity, a Foursquare app for avoiding sausage fests.

Assisted Serendipity is a simple little application that uses Foursquare checkin data to alert you when the “scales of love tip in your favor,” i.e. when the male-to-female is on your side at a designated bar, restaurant or venue.

Foursquare users can select the venues they want to watch and set their preferred guy-gal ratio, even if the preference is ridiculously one-sided at a 5:1 ratio. The app will then notify the user when that ratio is reached at one of their selected venues, and he/she can head on over and go in for the odds-in-their-favor kill.