Dunkin’ Donuts is offering a FREE medium beverage when you join their DDPerks Rewards Program for a limited time. The program is FREE to join and it gives you points for every purchase. You’ll also get a FREE beverage on your birthday and for every 200 points earned for purchases at Dunkin’ Donuts. They also have an iPhone or Android app that tracks your points, offers special members discounts, and can be used to pay for purchases at Dunkin’ Donut Stores. [Store locator]