Collaboration is easy with music

This live sample of the reactable in Berlin highlights for me how easy it is to collaborate with music. Stage actors, especially those in improv, do it with ideas, words and action. Writers do it well with something like wikipedia. The outcome is understood, but the collaboration effort to get there is missing (yes, you can look into the history pages). Online we are trying to make it a good experience at the Joyful Jubilant Learning blog. Are there other places to view collaboration in action?