I needed a timer to take online tests with (on an IBM PC).
And I found PC Timer. It seems ideal for this purpose:
In order to alert me when a timed test is nearly over, I configured it to run this simple batch file:
mode con: cols=100 lines=8
echo "Time's up"
Presumably, it will be useful in timing other things, as well.
Beyond the timer, it also has two alarms (for moments, rather than durations, as of version 4.0).
Copyright (c) 2012 Mark D. Blackwell.