Hourglass - Hourglass is the most advanced simple countdown timer for Windows.
Lassie Smoke - The modern way to quit smoking
wnr - Better than pomodoro, this timer app balances work and rest.
Smoke Free - Virtual "Quit Smoking Buddy" in your pocket
Free Countdown Timer - Free Countdown Timer is a free, full-featured and user-friendly countdown timer for Windows
Quitbit - A smart lighter and app to help smokers quit (pre-order)