Hourglass - Hourglass is the most advanced simple countdown timer for Windows.
Free Alarm Clock - Free Alarm Clock is a free, full-featured and user-friendly computer alarm clock for Windows.
TIMEBOX - An advanced timer for professional meeting facilitators
Digital Clock 4 - Beautiful customizable clock with plugins
Online Alarm Kur - Free online alarm clock, set alarm easily on your computer using the internet alarm clock without downloading any software, wake up in time with the loud online alarm clock.
AlarmDJ - Online Alarm Clock - Use YouTube videos or MP3 files as alarm sound. Works offline.