With more job seekers on the prowl, LinkedIn's traffic has doubled and its multiple revenue streams have turned into profit. Take that, Facebook and Twitter.
NEW YORK (Fortune) -- Looking for an online mirror of American economic woes? Check out the professional social networking site LinkedIn, where activity from Lehman Brothers employees and ex-workers spiked 315% from August to September of last year, when the bank was going through bankruptcy proceedings. LinkedIn's fastest growing region? Detroit.
