I've just finished writing a fairly exhaustive online instructional manual for bird photography, if anyone is interested:
The book covers equipment issues, field techniques, postprocessing, and distribution. The printed version is over 800 pages.
The online version is entirely free, and there are no advertisements or pop-up windows. I'm working on putting together a downloadable PDF, but for now it's HTML-only.
Please let me know if you find any errors---I'm sure there must be a few. Anyone who reports a nontrivial error will be listed in the acknowledgements after the next update. (Direct email is best, since I don't visit here often: I can be reached at email@example.com).