- PizzaTimer: http://ant4.com/PizzaTimer/download.html (countdown only)
XNote Stopwatch: http://www.stopwatch-timer.com/ (shareware $12)
- Alarm Clock 2: http://www.robbiehanson.com/alarmclock/index.html
I'm a Mac user so I use Alarm Clock 2 (which is excellent), but I had to use a Windows laptop for a while last week during which I used TimeAfterTime. In my experience it's the best one for Windows, but your mileage may vary.
Edit: Added SimpleTick, unaware's excellent contribution to this site.