Localmind is an intriguing little mobile app that has big potential.
It's a live Q&A service (see Quora, Answers, the departed Aardvark) about locations (see Foursquare, Facebook). If you want to know how crowded a bar or restaurant is, you pose the question on Localmind. People (but not all of them) who have checked in at that location on Foursquare get an alert and can reply to your query. Hopefully, you get your answer back quickly enough to matter.