Sleep Cycle - Bio-alarm clock that wakes you up at optimal times based on your sleep patterns.
Hourglass - Hourglass is the most advanced simple countdown timer for Windows.
SleepBot - SleepBot is a sleep tracking app available in Google Play and the Apple App Store.
AlarmDJ - Online Alarm Clock - Use YouTube videos or MP3 files as alarm sound. Works offline.
Talalarmo - Minimalistic android alarm
Free Alarm Clock - Free Alarm Clock is a free, full-featured and user-friendly computer alarm clock for Windows.