Blue Marble ice cream uses biodegradable stuff, they donate to charities, and use grassfed organic milk and other local ingredients. The price? about 30 cents more than your favorite uncle ice cream - worth it.
Then there's that truck, Van Leeuwen, parked in Soho on Green and Prince and also university and 12th and at McCaren Park's free movies. Artisanal, organic, really good ingredients, and their disposable products are made from renewable resources.