I used Processing to implement Adam Frank's "Performer," now running 10am-8pm every day in Anita's Way, between 42nd and 43rd Streets, just East of Broadway and Times Square. It will run until late November.

Web site is here: http://adamfrank.com/performer/performer.htm

It uses GSVideo to capture and process a live video stream, converts the amount of foreground and motion to a series of numbers, and triggers one of 100 sounds files to play. At its core, it is a simple program, though making the sound files trigger realistically and mixing the results took some care. The result is that "performing" in the spotlight earns a potentially enthusiastic response of applause and cheering.

Thanks must go to a number of people: the developers of Processing, GSVideo, and sox; forum users bustup, akiersky, and especially andres.