rigorousintuition.ca

Plenty of them, out of copyright and so on. Post links here.

Proofs of a Conspiracy Against All the Religions and Governments of Europe, by John Robison
The Road to Wigan Pier, by George Orwell

There's masses of stuff at Conspiracy Central: http://concen.org/tracker/index.php

Interesting and huge torrent called 'Occult Carrot', some good history works in there: http://thepiratebay.org/torrent/3746435

Part of Wombaticus's Brainsturbator library: http://thepiratebay.org/torrent/4016876/