My interest in so-called “illegal art” goes way back to the early 1990s when Negativeland ambushed U2 in the pages of Mondo to ask for a simple explaination about the 180-page lawsuit citing Negativeland for copyright and trademark infringment (See for yourself if they had a case).
The Chilling Effects Web site points users to an entire exhibit of Illegal Art. I particularly liked David Byrne’s IBM mash-up, but do take a turn around this monument to derivitative works in a variety of media.
PS — I realize this is all a bit dated, but interesting nevertheless. The articles section is also worth a look.