As a small company owner I want to completely endorse this comment. These "proofs" of a developers skills and technical interest are the hard requirements I have before conducting any interview. Naturally the "social proof" is also important but less common and more difficult to attain.

Even tiny personal projects demonstrating ones interest in keeping up with newer hot technologies like node, redis, backbone, etc mean a lot.

tl;dr Having a set of quality personal projects (github, live, whatever) is absolutely critical.