Running roughly south to north. Several of these web servers are currently under heavy load, so where there are mirrors I'll note them; in addition, some of the official maps are relatively large PDFs, so in some cases there are simpler to load images available.
Other sites with map collections: Core77, PSA: Hurricane Evacuation Maps; Hurricane Channel evacuation maps collection. A consolidated set of evacuation map data is in the FEMA GIS Data Feeds collection, labeled "HSIP Gold '10". Google.org's 2011 Hurricane Season has a set of map overlays which include the FEMA evacuation routes.
First pass of this is links only.
Maryland: Osprey Emergency Management Map from the Maryland Emergency Management Agency. Warning: this page came up with errors the first few times I loaded it. Evacuations: Ocean City (story, Baltimore Sun).
New York: New York City evacuation areas: official map (PDF); WNYC (Google map); Scribd map mirror (from PDF); Docstoc mirror (from PDF). Long Island storm surge flood map. Evacuations: Fire Island (ferry information); NYC Zone A, Rockaway (NY Times story; WSJ story))