It would be helpful for people who run multiple client if the Foldit client would somehow notify the user that it is idle. Some ideas for notification options: visual only; pop client to the foreground; audio; if audio, select sound to play; text user; IRC notification through client chat (because usually I keep one client up front, the one that chat works correctly on); email.

The notification (except for audio) should include the name of the puzzle open on the client that is idle (along with whatever general info might be useful--maybe the name of the computer it is running on).