Referee!

A simple app to be used as an electronic referee.
It's designed for sports like football, five-a-side, but it can be used for any sport with time periods, when a human referee is not available... It shows minutes:seconds since the match start, and signals with traditional, stunning referee whistles the end of each period (and if you like it can whistle the player changes as goalkeeper, too).
Plus you can insult at will, without risking expulsion! ;-)