After we sign up, what next?

S.F. Chronicle: CLICKING FOR CONNECTIONS: After a big splash, social networking sites (both business networking and dating) try to hold onto users.

Social networking, as the industry is called, has enjoyed phenomenal growth during the past year. Millions of Internet users have signed up with services such as Friendster, MeetUp and Tribe Networks, many of which are based in the Bay Area.

But the question remains whether the Web sites can keep users interested beyond the initial few months. After users link up with all their friends and browse their profiles — then what?

Update: Also a similar article today from the NY Times.