Besides transforming modern romance, online dating has spawned a $516 million industry, complete with its own market leaders ( and Yahoo), trade association, trade media (Online Personals Watch), and conference (Miami, Feb. 2 and 3).

But even as the industry matures, entrepreneurs continue to get into the dating game. Though most upstarts focus on demographic niches, a few try to come up with a new angle. For example,, a Dallas company, differentiates itself by relying on personality tests. Founder Herb Vest uses a proprietary 99-point formula to matchmake among the site's five million members, who pay $50 a month.

Other companies are tech-driven. Abe Smilowitz's Miami-based WebDate arranges dates via Web cams and VoIP lines. In New York City, meanwhile, Ken Deckinger and Adele Testani's HurryDate blends speed dating (meeting 20 or so singles in quick succession at an event) with a members-only website that lets people continue flirting online.

Now HurryDate is ramping up video-on-mobile phone applications, which "have the potential to revolutionize online dating," Deckinger says, "just as Internet dating revolutionized dating."