Free Alarm Clock - Free Alarm Clock is a free, full-featured and user-friendly computer alarm clock for Windows.
System Scheduler - System Scheduler for Windows, Free Task Scheduler Software replace Microsoft Windows Task Scheduler
Digital Clock 4 - Beautiful customizable clock with plugins
Task Scheduler - The Task Scheduler enables you to automatically perform routine tasks on a chosen computer. Task Scheduler does this by monitoring whatever criteria you choose (referred to as triggers) and then executing the tasks when their criteria are met.
G'Morning - Alarm Clock - When your alarm goes off, you will be asked to solve a simple multiplication question in order to turn the alarm off. The alarm will keep ringing until you answer correctly. Have a wonderful G’Morning!
Insane Alarm - Wakes you up no matter what! Features - obscenely loud blaring emergency alarm sound.