The US Postal Service has begun a 30th anniversary Star Wars tie-in by converting some of its drop boxes to look like R2-D2. Apparently there is more to come, including specially-themed stamps. The list of cities receiving the drop boxes is here, and a map of the ones “discovered” is here. My home town of Denver has one, but it’s not yet listed on the map.
UPDATE: The Denver mailbox is located at 299 Fillmore St.