From his blog Seth Godin lead me to Lula’s Apothecary serving vegan ice cream in New York City. It’s not about their ice cream or business model, but they also publish their daily servings on Twitter.
Every restaurant, bar, bakery etc. should have their daily specials published on Twitter !
Especially if they serve something I would make a detour for and make an impulse purchase. Ice cream being definitely one of the cases.
Monitoring customer response either on Twitter or with business results would definitely help to steer the business. And positive re-tweets would also serve as promotion.