Looks like the only counties so far with Obama carrying every precinct are Washingon, DC and Prince George's, MD. Any other (large) counties have this? Perhaps: Bronx, Manhattan, some in Bay Area, New England, Honolulu, St. Louis (city), St. Louis (MN), Hudfson, NJ, Baltimore...
McCain won several townships in St. Louis County, some chunks of "unorganized territory" plus the city of Orr (I'm using the Minnesota municipal definition of "city" here, Orr is a very small town.) For some reason the national park area of St. Louis is somewhat Republican (or more accurately contains some Republican areas.) Orr is in this area. The far southwest corner also contains some of the Republican voting areas. None of the population centers had any McCain precincts though.