Launch Clock - Set a launch date for your startup and stick to it
Hourglass - Hourglass is the most advanced simple countdown timer for Windows.
E.ggtimer.com - A simple countdown timer with an alarm for the browser.
SnapTimer - SnapTimer is a simple, free, portable countdown timer for Windows.
Departure - Your website launch checklist
Free Countdown Timer - Free Countdown Timer is a free, full-featured and user-friendly countdown timer for Windows