Hourglass - Hourglass is the most advanced simple countdown timer for Windows.
Gnome Clocks - Clock application designed for GNOME 3
Free Countdown Timer - Free Countdown Timer is a free, full-featured and user-friendly countdown timer for Windows
KTimer - KTimer is a little tool to execute programs after some time.
NetTime - nettime is a time & attendance software solution.
T-Clock Redux - T-Clock Redux in an enhanced fork of Stoic Joker's T-Clock 2010 with ISO week number support...