Android: Your device has individual volume levels for such things as media, notifications, phone calls and alarms. Slider Widget manages them all in one place.
You can configure Slider Widget to be colour-coded or uniform. Tap on any of the icons, and a floating box will appear with a slider that you can move up and down. Options for vibrate, silent and overriding the system volume are included on the low-end of the bar. Oh, and just for kicks, why not throw in a brightness bar too?
Slider Widget (free) [Google Play]