I've watched this 1966 video of Kermit the Frog riffin' on the fine points of visual and abstract thinking more times than I care to admit. I love it - its smart and tender.
More than a instrument, more than a social-tech app - how about a unitary-planetary experience on hearing others playing on the other side of the world and see their beauty rising to the heavens - WOW http://ocarina.smule.com/. Note: "one's mileage may vary."
Sometimes I don't know what I'm thinking until I try to say it (or in some way express it). In the act of expression, the externalization of thought, there is opportunity for increased refinement, clarity and understanding.