ITA, famously, uses Lisp. When I interviewed, only one of the interviewers did anything to check my claim that I had used Lisp slightly. (That one was a doozie, though—he handed me a printout of a function in Common Lisp and asked me what it did. I stared at it for about ten seconds, panicked by the DO loop—and then recognized the shape and said, "Oh, this is quicksort!" That was enough for him; he waved away further explanations and went on to more important questions. But I'd've been lost if I hadn't seen quicksort in half a dozen functional languages.)