I am not sure how prevalent they are elsewhere but here in the Toronto area they have started installing countdown timers in the traffic lights and to me they are a great idea. As a driver and a pedestrian you know exactly how much time you have before the light turns red and can judge and act accordingly. It is one of the better improvements that have come along.
That's a great suggestion. Major cities tend to have these at crosswalks -- I'm thinking Washington, DC, which has large red numerals, and Dublin, Ireland, which uses sound cues for pedestrians.