I've always hated that one about, "What are your strengths and weaknesses?" The interview guidebooks used to recommend naming a "weakness" that sounded admirable such as a "I'm a bit of a perfectionist," or "I work WAY too hard!"
I know someone in a high-tech corporation where they ask interviewees (all of whom have backgrounds in computer science, not civil engineering), "Why are manholes round?" It's a design question and also intended to see if they can think on their feet.