XNote Stopwatch - Try the most feature-rich stopwatch and timer software on the net for free!
TimeLeft - TimeLeft is a versatile desktop utility - it can be used as a countdown clock, reminder, clock...
Stopwatch - A Java countdown timer and stopwatch. Features a fullscreen and a resizable window mode.
Smart Sloth - Smart Sloth uses the concept of timeboxing, which is to allocate a set amount of time to each task, therefore, creating a deadline which can increase the productivity of the user.
ChirpyTime - ChirpyTime: Timer / Alarm Clock / Clock app for iPhone / iPod Touch
wnr - Better than pomodoro, this timer app balances work and rest.