Free Alarm Clock - Free Alarm Clock is a free, full-featured and user-friendly computer alarm clock for Windows.
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!
Gnome Clocks - Clock application designed for GNOME 3
Insane Alarm - Wakes you up no matter what! Features - obscenely loud blaring emergency alarm sound.
AlarmDJ - Online Alarm Clock - Use YouTube videos or MP3 files as alarm sound. Works offline.
Alarm Clock Xtreme - Alarm Clock Xtreme: Alarm, Stopwatch, Timer (Free) is the most popular alarm clock app created and published by AVG Labs for both iOS and Android devices.