Do you have a Starbucks' gift card? If so, register it here and you'll receive a free drink on your birthday! Just be sure to enter your birth date and also opt to receive mail so they can send you the coupon.
Don't have a Starbucks' gift card? You can redeem some points at Swagbucks for one or buy a $5 one and register it just so you can get the offers. Often the offers they send require that you buy one drink to get another one free, but not always. And I love Starbucks so any free drinks from them are great in my mind!