I've search the forum and done google searches but have still not been successful in finding a countdown timer that works on a 8120 Pearl. There are a couple of free ones mentioned in these forums:
Free chronograph new CountDown Timer (need opinions)
but one of them would not access the tones / vibrate function properly and the other threw up an error when I first tried to launch it so I'm guessing neither of these function well on the 8120.
Has anyone managed to find one that works really well? I don't mind paying if it does the job properly.