QuickVolume

This is a simple app that lets you quickly change the phone's volumes to three different levels: mute, full volume and user-defined.

Just launch the app and press one of the buttons to change the volume.

This is great when you're in a theater or at work and need to mute the phone easily. Set the volume to max when you're playing a game or listening to music. Set the volume to your preference when you're at home.