Viintage is a neat site that developed by a husband and wife graphic design and photography team. Viintage features collections of vintage posters, postcards, and various printed advertisements that have been released into the public domain. Viintage hosts thousands images organized into dozens of categories like vintage travel posters, classic alphabet learning books, and vintage nursery rhymes images. You can download medium resolution (600px-3000px) copies of the images for free and higher resolutions are available to premium site members.
Applications for Education
Some of the travel posters available through Viintage could be good for students to use in presentations about the history and or appeal of various places around the world. Many of the Viintage graphics could be used as part of a lesson on advertising methods (endorsement, appeal to emotions, etc) as well as lessons on the evolution of graphic designs.
You might also consider having students use the Viintage graphics of children's stories to develop audio slideshows in which they narrate they stories depicted.