My Seiko watch is from their "Kinetic" range. It never needs new batteries and never needs winding. Instead, there is a little weighted wheel inside the watch which swings around as the watch moves and produces power (You can see all this through a window in the back of the watch). If I leave the watch completely still for a couple of weeks, it'll run down.This idea is for a flash memory mp3 player (i.e. low power consumption) based on the same principle.-- hippo, Apr 13 2005 Interesting - so, lower battery lifetimes if you listen to ambient music?-- hippo, Apr 13 2005 I had imagined an MP3 power supply hooked into a bicycle. Slow down and the music stops.-- Worldgineer, Apr 13 2005 random, halfbakery