Facebook showed off a new service for its social networking site that will allow people to take their Facebook profile and use it on other sites around the Web.

Called Facebook Connect, the service was announced back in May and received its first full public airing Wednesday at Facebook's f8 developer conference in San Francisco, complete with demonstrations of how it will work with Digg, Citysearch and Six Apart.

When a person Diggs a content item on the Digg Web site, the login box will give them a choice of logging into Digg or Facebook. If they choose Facebook, then the items they Digg will appear back in their Facebook activity feed. They'll also be able to see which of their friends are on the Digg site and interact with them there.

If they log in with their Facebook account on Citysearch, the photo they use in their facebook profile will appear next to their posting on Citysearch, along with a link back to their Facebook profile. Their Citysearch review can also appear back in their Facebook feed.

The service was the highlight of Facebook founder Mark Zuckerberg's speech at the start of f8. He called it "our version of Facebook for the rest of the Web." The privacy settings in Facebook are also carried over, so people can choose which photos and other bits of information will be visible, he said.

Some developers here enthused over the service as a way to boost traffic to their applications and Web sites. People can use services at other sites more easily because they won't have to register -- they'll be using their information from Facebook. And activity on other sites will appear in their Facebook feed, so their friends will see, in effect, an advertisement for the other site.

"I think they made developers really happy; it just depends on whether users will buy into it," said Michael Dory, a research director with games development company Social Bomb.

Facebook Connect will compete with the MySpace Data Availability service, also announced in May. Developers can start working with the Facebook Connect "sandbox" now and a full roll-out is expected in about October, Zuckerman said.

Much of Facebook's growth this past year has come from international users, Zuckerberg said. International users accounted for about 50 percent of its visitors last year; the figure now is 68 percent, or more than two-thirds, he said.

Facebook now has about 90 million users, according to Zuckerberg, up from 24 million last year. It still ranks far behind MySpace in terms of daily visitors, according to Internet measurement company Hitwise. It gave MySpace 73 percent of the visits to social networking sites in June, but Hitwise also said that Facebook is growing at a much faster rate.