Why not just pair with the interviewee for half a day or a day? You will learn how they think and work and if you like them. It's a riddle to me. I've never heard from anyone actually trying it and not being happy with the insight won.
Of course, github is the real resume now.
My new startup is focusing on doing exactly this --- bringing together as many sources about engineers together as possible, and putting them all in one place. It's still very early, but I'd love HN's feedback. http://proovn.com