David Heinemeier Hansson from 37signals on hiring developers.
I’ve known fabulous programmers flame out in the quizzing cage and terrible ones excel. So unless you’re specifically hiring someone to design you the next sorting algorithm, making them do so on the white board is a poor gauge of future success. I've read many articles on this subject: how to ace an interview for a developer position. Even for front-end positions, questions about algorithms and similar "puzzles" arise. Sorry, but I actually think you have to tailor the interview material for the practical assignments the interviewee will receive.
Today, most developers (at least web developers) don't write computer science-y stuff all day long. We solve real world problems, read documentation, build scalable systems, cooperate (social skills are vital!), implementing other people's code, and more. Quizzes are fine, as long as they are relevant for the actual work I am going to do.
(Also: see 37signals job listing for an interface designer position some time ago, I wrote about and linked to it).