Two biggest things in my personal experience that ended up with amazing hires. Unashamed to admit they don't know something in the interview, treat it as a matter of simple fact - they don't know yet, but can find out. Program in multiple languages / explore languages / can speak about strengths and weaknesses across languages.
In my (obviously limited) experience, high GPAs have correlated to poor or even poisonous personalities. Often arrogant without merit, unable to change positions because of ego, and with an inability to adapt and learn.
Google appears to have done an experiment on a much grander scale and come to similar (but IMHO a little better written up) conclusions: http://qz.com/180247/why-google-doesnt-care-about-hiring-top...