"- "While LinkedIn.com is a free site, and intends to keep providing a free service in the future, it plans to launch a premium service that would have additional features around the end of the year." - LinkedIn users accept 83 percent of referrals - 840,000 members - 10,000 are venture capitalists. - Bay Area is the densest concentration of users, with 120,000 members there. - Most members tend to be between 30 and 55 years old. - 97 percent of LinkedIn users join based on invitations from existing members."