Ration Coupons on the Home Front -- an archive of digitized WWII ration cards and other ephemera. From Duke University Libraries. They also have a bunch of other interesting digital collections including AdViews, which is an archive of advertisements from the 1950s to the 1980s.
Two literary ones-- Orwell Diaries and The Edgar Allen Poe Digital Collection.
Ethnologue - Languages of the World. A huge site, accessible to anyone, cataloging all of the world’s 6,909 known living languages.
The British Library's Archival Sound Recordings-- almost 24,000 items are available on here to the public including music, language and conversation, and wildlife recordings.Actually the whole British Library online exhibitions site is incredible. Their virtual collections include historical maps of London, Victorian ephemera, and digitized manuscripts and sketchbooks, among other things.
