Hoffman's investing portfolio reads like a directory of the most notable consumer Internet companies of the past decade: Digg, Flickr, YouTube, Facebook, Zynga. The 42-year-old Hoffman, who has a philosophy degree, emanates a certain type of brilliance that makes him a go-to adviser for entrepreneurs. Put simply, he gets how to grow a viral business. (Exhibit A: LinkedIn, which he founded in 2003, is flourishing.) With investments in 80 companies, Hoffman officially turned pro last year, joining Greylock Partners. --J.H.
NEXT: Investor runner-up: Vinod Khosla
Last updated July 09 2010: 1:19 PM ET