These days nearly anything with a copyright gets pirated within minutes of its release—and, with leaking a constant problem, sometimes even earlier than that. Archival music and movie torrent sites collect these rips, building massive libraries that contain the large majority of our collective cultural output. If you want a piece of media from the last 50 years, and you know where to look, you can find almost anything.
Certain works are difficult to source, and in the digital underground, they can achieve almost legendary status. Lost movies; shelved albums; out-of-print books — the harder they are to find, the more the pirates want them. These are the Holy Grails of Internet piracy.