www.gutenberg.org
Thanks, Frank
Also always check http://books.google.com/bkshp?hl=en&tab=wp
Most old books out of copyright can be downloaded free as a PDF or some as other types of e-books. Lots of free old technology and any type of book really.
Also - Google has reached a court agreement that may make millions of lost - out of print books available soon.
http://books.google.com/googlebooks/agreement/