Free Alarm Clock - Free Alarm Clock is a free, full-featured and user-friendly computer alarm clock for Windows.
Pzizz - Sleep at the push of a button! Now with "Focus"
Gnome Clocks - Clock application designed for GNOME 3
Awaken - Wake up to Awaken playing your favorite music.
AlarmDJ - Online Alarm Clock - Use YouTube videos or MP3 files as alarm sound. Works offline.
Enough Sleep - Boost your performance by getting enough sleep!