Online version of the 37 Signals Book. It's basically a book version of a lot of their popular blog posts. Definitely worth a read.
http://gettingreal.37signals.com/toc.phpFree opensource book about understanding and using the gimp for image creation and manipulations.
http://gimp-savvy.com/BOOK/Online version of The Art of Unix Programming book. Same as the print version from Addison Wesley. Good guide about creating application on unix, philosophies and things at the level of code and interaction with the unix kernel and subsystems.
http://www.faqs.org/docs/artu/index.htmltags: books ebook linux programming unix
Community college open textbook collaborative is a website that has links to all sorts of free university level text books that you can download and read.
http://collegeopentextbooks.org/home.htmlFree online version of the Real World Haskell book by Bryan O'Sullivan, Don Stewart, and John Goerzen.
http://book.realworldhaskell.org/read/The free online version of the django book from the creators of django.
http://www.djangobook.com/en/2.0/Free online version of the WIP book CouchDB- The Definitive Guide from O'Reilly
http://books.couchdb.org/relax/Free linear algebra text book at the level of a first undergraduate course in lnear algebra
http://joshua.smcvt.edu/linearalgebra/tags: books ebook linear-algebra maths