I don't know how many people know of this but I'm sure there's at least 1 person who doesn't.

There's a site called Project Gutenburg and what they do is publish books online that are in the public domain. I have known about this site for many years, but for some reason I haven't gone in over a year. Here are some highlites of the site. They have over 13,000 books online, (although sort of old) they have "The best of Gutenburg" CD and DVD ISO's to download, they have audiobooks that you can download, some human-read some computer-read, they support P2P networks (finally a legal use for them) and much more. I would recommend anybody go visit this site.

If you really like it and want to contribute, they have what's called distributed proofreading. If your good at english then you can get a page a day to help proofread.

The CD or DVD images make great (and cheap) christmas presents for the avid reader. Or for the person that would rather listen then read you can download one of their audiobooks.

Hey Zuggy
O'Reilly books have one too

http://www.oreilly.com/openbook/

floppy

For great online learning (excellent linear algebra course!), it's hard to beat MIT's OpenCourseWare

Those all look too cerebral for me.

Baen Books - entertaining pulp SciFi

http://etext.library.adelaide.edu.au/aut/
http://turn.to/project.unicorn
http://readytogoebooks.com/Authors.htm
http://www.geocities.com/thenietzschechannel/
http://fleursdumal.org/

Lord Byron's:
http://www.geocities.com/Athens/Delphi/7086/donjuan.htm

Another good site with lots of old pulp fiction books like Doc Savage and Conan is
Blackmask Online : You can't renew as author if you're dead
http://www.blackmask.com/