Sleep Cycle - Bio-alarm clock that wakes you up at optimal times based on your sleep patterns.

Alarmy - World's most annoying alarm app

Sleep as Android - Common alarm clocks ignore your sleep cycles, they wake you on schedule no matter your are currently in your deep sleep. Waking up from deep sleep is unpleasant, it makes you tired and it may negatively affect your productivity during the whole day.

Galarm - Social alarm clock and reminders

Alarm Klock - A better alarm clock.

Free Alarm Clock - Free Alarm Clock is a free, full-featured and user-friendly computer alarm clock for Windows.