Hourglass - Hourglass is the most advanced simple countdown timer for Windows.
TimeLeft - TimeLeft is a versatile desktop utility - it can be used as a countdown clock, reminder, clock...
wnr - Better than pomodoro, this timer app balances work and rest.
SnapTimer - SnapTimer is a simple, free, portable countdown timer for Windows.
No Frills Timer - No Frills Timer keeps track of the amount of time you spend connected to the Internet.
Free Countdown Timer - Free Countdown Timer is a free, full-featured and user-friendly countdown timer for Windows