Sleep Cycle - Bio-alarm clock that wakes you up at optimal times based on your sleep patterns.
Ruya - A calming space
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.
Defonic - Create a unique sound environment at home or in the office
Talalarmo - Minimalistic android alarm
Spaces.FM Beta - Binaural sounds to improve focus and boost your productivity