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

Power Alarm Clock - Free - Powerful alarm android app to manage even the most complex requirements.

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.

AlarmDJ - Online Alarm Clock - Use YouTube videos or MP3 files as alarm sound. Works offline.

Sleep Time - Alarm Clock - Sleep Time provides insight into your sleep patterns. By tracking your level of movement throughout the night, Sleep Time generates customized sleep data in easy-to-read charts.

Gnome Clocks - Clock application designed for GNOME 3