It's surprising to me that so many in this thread are asking if these rankings are legit. Of course they aren't -- they operate on a simplification that trade accuracy for convenience. It's one developer's side project...many professional companies and analysts have failed to encapsulate the worth of a human being as a number, why should this developer be any better?

That said, I imagine a lot of headhunter companies use the same kind of heuristic, which is probably why I get so many unsolicited interview requests despite my lackluster activity (I'm in the top 200 developers of Ruby in New York, and #3200 in CSS...of the entire world)