PhotosNormandie is a collaborative collection of more than 3,000 royalty-free photos from World War II's Battle of Normandy and its aftermath. (Photos date from June 6 to late August 1944). The main link goes to the photostream. You can also peruse sets, which include 2700+ images from the US and Canadian National Archives.
Agence Eureka is a French language image-blog with hundreds or even thousands of scanned illustrations, mostly from mid-20th century French schoolbooks, educational material, magazines, and ephemera. The current front page is slightly NSFW. Some of the categories include anatomy 1 & 2 (mildly NSFW); chocolate wrappers/trading cards; bricolage; decoupage (cut-outs); math education; playing cards; books and magazines; cars; cinema; orientalisme; sport; mild pin-ups; and many others (scroll all the way down the right to see the tags). [more inside]
Insecula. As the Wiki says:
Insecula: L'encyclopédie des arts et de l'architecture is a French language art website containing images and descriptions of thousands of works of art from major museums and collections in France and elsewhere, including the Louvre, the Musée d'Orsay, the Palace of Versailles, the Centre Pompidou, the Metropolitan Museum of Art and the MOMA.But it's not just museums and art. It's got Mayan ruins, Manhattan and Brooklyn, and of course lots of Paris streets. I can't believe plep hasn't posted this already...