Service - Live Timer

It would be great to be able to run a live timer during service that showed how much time was remaining for each current item that was also recorded for future reference.
For example, if we have 25 minutes for the teaching, then the visible timer would start at 25 minutes and count down, showing how much time is left, and then when the teaching is over, it would record how long the teaching was before moving on to the next item.