I don't know what they're rightly called, but you know the kind still common at train stations and for a long time at airports in the past, where the board has to cycle through each letter of the alphabet, and has special fields like "delayed 15 min" or "boarding"? I'm just curious for nostalgic reasons -- I wonder if any of these exist in large airports still -- they're kind of neat I think. Of course in lots of places you have the segmented letter LCD (?) boards, the intermediate between the old flapping boards and the modern plasma screens, and these sort of give you the same feeling. But nothing beats the sound of the mechanical characters flipping around every few minutes, I remember...