Be Focused by XWaveSoft - Simple Pomodoro timer in your Mac's menu bar
Hourglass - Hourglass is the most advanced simple countdown timer for Windows.
Doropomo - Inverted Pomodoro focused for a truly work/life balance
wnr - Better than pomodoro, this timer app balances work and rest.
Flow - Stop managing projects from your inbox.
Free Countdown Timer - Free Countdown Timer is a free, full-featured and user-friendly countdown timer for Windows