One of the best sources for Queens photographs, especially from the 1940s and earlier, is New York City's Department of Records.
The Department's NYC Municipal Archives has photographs of every residence in Queens and all of NYC from 1939 to 1941 (originally used for tax records). Send in a request for a photo of a specific house or building that you or a family member lived in, and you'll receive a print of the home in the mail. It's a great gift to stir childhood memories, and only $35 or $50 depending on print size.
Unfortunately, a lone commercial dealer -- Queenspix.oom -- that specialized in Queens, sells prints of historic photos of Queens seems to be on hiatus.
The Queens Library's Long Island Division has a local history collection, including over 100,000 photographs, but unfortunately, they're not available online except in small doses. Prints can be made from the collection. Contact the Long Island research librarian for more information (718-990-0770).
Good luck with your hunt, and email me if you find any troves of Queens photographic treasure.