Open Culture provides links to a whole load of free material including films, audiobooks, textbooks, ebooks, MOOCs, course notes, language lessons, audio and video clips and thousands of images. The focus is on educational and cultural materials.

All of the material is collated from other sites but it makes for a brilliant place to find things you never knew existed. For example:

Try exploring on a spare summer afternoon while you’ve got time to while away the hours.