Personaly i've found that shifting away from the formality of an interview, turning it into an agenda driven chat to be the most sucessful way of conducting interviews.

Anyone and everyone can blag it with rehearsed answers from commonly used interview techniques.

Take it onto a personal level, find out what the person is like and take it from there.

You aint going to find out what a potential employee/work M8's personality is like based on an interview other wise.