Hi,
I found an interesting web-site,
http://www.freetechbooks.com. It is exactly what it says, a collection of free technical books.
Topics include:
Computer Science
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Introduction to Programming, Algorithms and Data Structures, Object Oriented Programming, Formal Method, Logic Programming, Compiler Design and Construction, Computer Network, Information Management, Software Engineering, Image Processing, Game Development
Operating Systems
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UNIX, Linux, FreeBSD
Programming and Scripting Languages
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Assembly, C/C++, Java, Lisp/Scheme, Perl, Python
Enjoy! :)