I'm blogging this and I'd just like to say I have no guilt in doing so, as I have personally sent over a thousand dollars Mr. O'Reilly's way over the years. An HTML version of a book is not a replacement of a book, and I would continue to buy books even if all of them were available online. Maybe once adaptive paper screens are widespread, that will change.

This site has the O'Reilly collections on: Java, Perl, Networking, Unix, Web Development, Linux Web Servers and Oracle.

A very, very handy resource.

O'Reilly Reference Library for Free : Ukraine Rocks