Starbucks (NASDAQ:SBUX) is giving customers around the world a bold incentive to swap the paper cup for a more eco-friendly option. On Thursday, April 15, the company will reward customers who bring a reusable tumbler into participating stores with a complimentary brewed coffee. This effort is just one of the ways Starbucks is collaborating with customers to reduce environmental impacts. The company has offered customers a discount for tumbler use since 1985. (4/15/10)