The Gym Boss Interval Timer.
I got a Gym Boss a few weeks ago and I love it. No more watching a clock or stopwatch for intervals, I just listen for the beep.
This thing is truly, painfully awesome. It is a definate love/hate relationship. It never misses a count, always keeps time and it never, ever apologizes. The beeping sound that it makes taunts me and calls me a sissy sometimes, but it makes things like the Dane's VO2 max workout simpler because there is no need to watch a clock, just listen for the beep and revel in the misery.
I have been using it strategically for the Secret Service Snatch Test too. I set intervals at :50 and :10, snatch 10-12 reps per arm and set the KB down at the first beep and go again at the second beep. It's horrible, but in a good way.
If you are doing any kind of interval training I highly reccomend it.