New York and New Jersey birders are excited about the appearance of an adult ivory gull in Piermont, N.Y. Ivory gulls are birds of the Arctic, and are rarely seen on the east coast south of Newfoundland. There are good accounts of the sighting at Lovely, Dark, and Deep; Hawk Owl's Nest; and City Birder. The sighting even has Maryland birders excited.
Closer to D.C., but still out of my reach, unfortunately, a thick-billed murre has been spotted at the Ocean City Inlet. See the details here and here.
Update: The ivory gull is now gone.