Here’s a brilliantly simple idea. Agora is a service built on the Foursquare API, designed to match you up with likeminded folk when you check in at a location.

Let’s say you arrive at a bar where twenty others are checked in. Agora will work its magic in the background, using the Twitter API to analyse who you share similar interests with. The service will then send out a tweet telling you and the others similar to you that you should meet, giving them scores based on their similarity to you.

If you’re somewhere like New York or London, with a highly active Foursquare community, Agora could be a useful networking tool. Foursquare co-founder, Dennis Crowley recently described the app as a “Hot use” for the API, and suggested improving the app by filtering out people who you check in with on a regular basis.

Screen shot 2011 03 17 at 10.34.25 Agora helps you meet new Foursquare friends when you check in

Agora was built in five hours by New York-based at the first Foursquare Hackathon. Its creator, New York-based Pierre Valade is planning to build the service into a social calendar solution that simplifies scheduling in the same way that Dropbox made filesharing refreshingly easy. Valade was one of the entrepreneurs pitching Union Square Ventures VC Albert Wenger in elevators at SXSW last weekend. Here’s his brief, literal ‘elevator pitch’.

Agora at Courtyard by Marriott Austin Downtown (Convention Center) by albertwenger

Agora is quick and easy to try. Just connect it up to your Foursquare account from its website and you’re good to go.

Image Credit / Nan Palmero