We ask people to pair-program with an interviewer on a realistic task. No tricks, no brainteasers. We just get to see how people do the job we want them to do.
Just curious, as I do something similar but solely to see how the person writes code. Folks are free to pair-program or not once hired.
I've found almost everyone needs help on some simple part of the task, and how they respond to the help is pretty useful information.
It is an enormous help toward glimpsing the mind of the programmer as they program.