I've liked the downloadable stopwatch from www.online-stopwatch.com for some time now. I noticed today that they've added some great new versions.Theres an egg timer, a clock and a bomb with a fuse!! All with variable times.
www.online-stopwatch.com/download-stopwatch/
The Kent one doesn't really compare, but just in case, here it is:
www.kented.org.uk/ngfl/games/countDownClock.html
Have fun
James:)