I've said it before, but there are few things quite as annoying (or embarrassing) as having your smartphone go off at a time where it just shouldn't happen. Imagine a nice, intimate evening with your significant other; you dim the lights, snuggle up, and "this classic" comes on. Or, your phone goes off in a meeting, and your boss gives you that look.
To combat these issues, Android dev zevele created Ringer, which he actually started for his wife who was missing her old ringer modes. Ringer is a bite-sized app that gives users the ability to customize how and when your device rings.