I knew a guy who would ask the binary search question in interviews (i.e. "you have an array of sorted values, what's the fastest way to find if an element is in the array?"). I always felt like this was an unfair question to ask somebody as well - it doesn't seem like something you'd be able to come up with on your own if you hadn't seen it _in an interview situation_. OTOH it's a quick way to screen people who actually did a CS degree.