If business networking weren't meant to be a controlled, measured process, then why did you just hand that guy your card instead of your whole wallet? Letting you maintain that same control over online biz networking, WhoDoYouKnowAt.
Recently unleashed in free base-level form by an ex-Dell/Oracle exec, Dallas-based Who@ uses "bank-level security" and a five-tier access system to give users wide selectivity over the revealing/
concealment of their contacts' info, thus avoiding the overly public, orgiastic contact groping that's led true ballers to drop less discriminating sites entirely. First, download all your peeps from Outlook/Gmail/Yahoo/etc, then for anyone who's already a Who@ member or whom you choose to invite, assign a "Level of Trust" that dictates exactly what of your deets can be accessed (if they accept, they'll do the same for you): Closest Contacts shares all info; Close Business & Social Contacts closes off Network Notes; Business Contacts closes off personal phones/emails; Business Colleagues closes off all contact info except name/title/company; and Invisible Exchange actually keeps you anonymous, until you decide to help someone with a specific request for introduction -- thereby avoiding the classic "Don't Want Loser Co-worker To Know You Don't Want To Intro Him To Anybody" dilemma. At the higher levels, you can tag other peoples' contacts to facilitate your own searching; you can also receive notices when someone's info's outdated, download vCard data, set up special "In-Company" functionality, and use their proprietary "Relationship Rank" to algorithmically order searches according to whoever's the best contact for your current needs -- though you don't need an algorithm to tell you that, for all new drug needs, you should reach out to Huey Lewis.
Upcoming enhancements include compatibility with major enterprise software, fee-based memberships for larger request/alert/contact-sharing volumes, and custom alerts for when specific places/companies/people/tags show up in your Who@ contacts' profiles -- so you'll know exactly when to reach out to someone tagged "Left Marriott Bar With Some Idiot's Wallet".