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

Gnoosic - Even if you don't know what you are looking for - gnod will find it.

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.

Musicroamer - A visual Pandora for discovering new music

Talalarmo - Minimalistic android alarm

TasteDive - TasteDive recommends similar music (musicians, bands), movies, TV shows, books, authors and games, based on what you like.