Android: Alarm clock apps are typically bare-bones affairs, but Alarm Clock Ultra manages to pack in a shocking number of features into a beautifully packaged Android app.
Each alarm you create comes with a huge array of customisation options. You can gradually increase the intensity of your chosen alarm sound, limit the number of times you can hit snooze, and even force yourself to solve maths problems or puzzles to shut it off in the morning. Other features include a quick-start nap mode that lets you set a napping alarm with one tap, a built-in egg timer for boiling a perfect egg, and a news ticker that previews your overnight social network notifications as you wake up.
Most features are available in an ad-supported free version, but $3 gets rid of the ads and unlocks the whole app.