From Holy Mackerel Software:
Minute Timer for Linux is a utility to help people time events and have lost their egg timer. Set up an event of any number of minutes and seconds (default is one minute). The ticking, 10-second warning and final buzzer sounds are all configurable. A simple application, but surprisingly useful for timing 20-30 minute presentations and talks, for games, cooking or exercising. No need to watch the hourglass or wait for the sand to return to the bottom.