CHICAGOAll 17 customers at Chicago's Urn coffee shop were billing third parties for time spent there. 'The people on laptops are web designers, unless they have big headphonesthose are either musicians or producers,' said the Urn's owner, Maria Carmichael, who wrote her coffee shop's business plan in a coffee shop. 'And Mario, who bills for time spent here even though he shouldn't, sells espresso machines.' Carmichael added that she conducts her second career, as a theater manager, on her Powerbook, using the cafe's wireless connection. 