I am not sure if this is in the correct section, as it is not strictly print, so I apologize in advance, and Bartender, please move to the correct forum if not.
I have been turned on to an iPad app called "NYPL: Biblion". It's concerned with the 1939-40 world's fair in New York, and it contains video, photographs, documents and much more, all from the New York Public Library archives.
All this information and its free! More information is here: