Unity Singletons - Life Across Scenes

In finishing out one of our titles, we sought to have uninterrupted music across several loaded scenes.   

The following article on Unity answers has a great Unity singleton model that can be used with objects to create this:

http://answers.unity3d.com/questions/11314/audio-or-music-to-continue-playing-between-scene-c.html

This is also an excellent way to optimize loading for levels that share content.   By creating a singleton container for scene objects, you can ensure that prefabs are loaded only once across scenes.