Hourglass - Hourglass is the most advanced simple countdown timer for Windows.
Countdown Screensaver - A Mac screensaver for counting down to a date 🖥🕐
Free Countdown Timer - Free Countdown Timer is a free, full-featured and user-friendly countdown timer for Windows
Email Taco - A free email countdown timer for expiring offers
Be Focused by XWaveSoft - Simple Pomodoro timer in your Mac's menu bar
Countdown to Inbox Zero - Always respond on time