"Send your location in by SMS at any time to 106920052131"
Wozone 我族网 is a free online social networking service that can also be used on your cell phone. You SMS your location and it tells you who is nearby that you might want to meet. It adds location to the usual online China features: chat rooms, BBS, photos and profiles, different "tribes" 部落 that you can search among including everything from geographic region to military interests. Most popular are fashion and feelings. Of course this kind of thing depends on a critical mass--the more users, the more valuable it is to other users--and there are no numbers on the site telling us how many people are using it. The locations themselves are quite broad areas within the city, such as "the zoo," or "Sanlitun" in Beijing. Presumably users could then SMS one another with more specific information if they were interested.
Here's a screenshot of one Beijing user who has input his location at Tiantan and Dongdan over one evening in Beijing.