American Memory provides free and open access through the Internet to written and spoken words, sound recordings, still and moving images, prints, maps, and sheet music that document the American experience.
Creative Commons provides free tools that let authors, scientists, artists, and educators easily mark their creative work with the freedoms they want it to carry. Search for audio, video, images, text, and more.
Access to over 600,000 images from primary sources & printed rarities in the collections of The NY Public Library, including illuminated manuscripts, historical maps, vintage posters, rare prints & photographs, illustrated books, printed ephemera, & more.
The Graphics Fairy posts a free piece of vintage clip art every day, perhaps useful for your next craft project. There are more than 1,000 graphics to choose from, plus tutorials showing different methods for transferring images—a lovely example is this drawer knob project. (via How About Orange)