Old story, but I came across it and thought it was interesting. Short story...a famous violinist (if you know violinists, I guess) Joshua Bell went incognito in a DC subway and played for free for 45 minutes on a Stradivarius that he reportedly paid $3.5 million for. This is normally a gentleman that sells out venues and he collected a little over $32.
http://www.washingtonpost.com/wp-dyn/content/article/2007/04/04/AR2007040401721.html
http://www.washingtonpost.com/wp-dyn/content/article/2007/04/04/AR2007040401721.html