Brian Wood is famous for the graphic novel Channel Zero. When I heard that he was offering a 17MB download of a work he's calling Public Domain ... sketches, character studies, found art and photographs, short stories ... everything that informed him in making the story, but had not yet made it into print.
The real thrill is seeing the "what went into" and the unfinished test sketches and drawings. Sometimes, the best art is 'undone'.
There's a great amount of found stuff, as I menched, but one which really caught my eye was apparently taken from a subversive flyer tacked to a 'phone pole in NY, one which even some (well, probably a great many) people in Portland can even relate to:
It's challenging for those in thier comfort-space.