Brightkite

www.brightkite.com

September unique visitors: 147,264
Change from August: -1.5%
Funding: $1 million from undisclosed investors

Why it's unique: Twitter is often used by participants at large, tech-related events, such as Austin's annual South by Southwest festival, to share opinions on presenters and coordinate after-party events. But what if your tweets could be viewed by everyone at the festival (or in close proximity), rather than just the attendees who know you? That's the idea behind Brightkite, which lets its 50,000 users "check in" at any location and find out what other nearby Brightkite users are doing.

How it plans to create revenue: Soon after Brightkite comes out of a private test phase in November, it will focus on integrating location-based ads. Founder Martin May says local vendors, such as an Italian restaurant, will be able to serve ads to a nearby Brightkite user who lists spaghetti as her favorite food in her profile. The site also plans to sell user analytics to local vendors, to help them discover clues about where their customers have been before they walk in the door. This model will require scale, May says.