Search Engines and Lists

• ebooksearchr - probably the best starting place
• “Best Places to Get Free Books - The Ultimate Guide” - includes lots of links to real-world book swapping sites as well

General Collections

• Project Gutenberg - still the best source of public domain titles in multiple formats
• Internet Archive - it can be a bit of a chore to slog through the unfriendly interface, but you can find lots of public domain material here in multiple formats
• Wowio - ad-supported PDF files and therefore not Kindle-friendly, but otherwise free. Site is down as of mid-July but promises to be back up soon.

Sci-Fi and Fantasy

• Baen Free Library
• Tor Books - sci-fi “supersite” offers free downloads of stories

Tech and Computer Books

• http://www.freetechbooks.com/
• http://www.pdfchm.com/
• http://www.realtimepublishers.com/
• http://itdiscover.com/links/
• http://www.phatsayar.blogspot.com/

Magazines, Trade Publications, and Miscellaneous Business/Trade Books

• http://www.tradepub.com/
• http://e-books-for-everyone.blogspot.com/
• http://www.asiaing.com/
• http://www.ebooksbay.org/

Audiobooks

• http://www.audiobooksforfree.com/
• http://podiobooks.com/
• http://welltoldtales.com/ (sci-fi, horror, and hardboiled/pulp stories)
• http://www.nokia.com/A4632325 (note: this may only work on Nokia devices)

Unsorted

www.bookyards.com/

www.librarything.com/

www.ebookshare.net/

www.ebooksclub.org/

www.digitalbookindex.­org/search001a.htm

www.bookshub.org/

www.bartleby.com/

en.wikipedia.org/wiki/­List_of_digital_library_projects

arthurwendover.com/

www.textfiles.com/

www.ibiblio.org/

netlibrary.com/

www.memoware.com/

http://http-server.carleton.ca/~nholtz/ElectronicPublishing.html

http://freeonlinebooks.blogspot.com/2005/10/other-books.html