I have been a member of LinkedIn for a couple of years, but have not used it at all to market my business.  I just got a short email from the service that shared a video of a small business owner , Sasha Strauss from Innovation Protocol who has used it to generate lots of referrals.  I thought it was really interesting, and when my book is done (ahhh!  less than 6 weeks!), I will definitely look into using LinkedIn more effectively for marketing my business. Worth pondering!