As part of our interview process for new engineers at Ephox the final stage is the Coffee Interview.
The Coffee Interview involves everyone in the the team, except the manager, going out with the potential hire and having a coffee. While discussions can be technical, it's not a technical interview but rather a chance for everyone involved to get to know each other. At the end of the coffee I get consensus from the team as to whether we should hire the person or not.
What we are trying to do in this interview is determine if the team can work with the person, and the person can work with the team. It's a case of ensuring the hire is a good "fit".
By involving everyone the person will work with, we are essentially building an emotional contract between the team and the new hire. These people are the ones who can exert the most influence over the success of the new hire and as such, the Coffee Interview provides a way to invest them in the success of the person.