Coffee at Starbucks. I go to Starbucks at least twice a day. I don't get a full eight hours of sleep most nights as a result of a) my 3.5 year old boy waking me up, b) staying up late working on photographs etc., or c) both "a" and "b". So the caffeine helps me to be productive at my real job. Fortunately, Starbucks is right across the street from my office.