http://en.wikibooks.org/wiki/
It's a wiki-like informative booksource with mainly their own works (the works of multiple artists).
You can download the books (in a legitimate way) just like wikipedia.
You can get them by saving pages manually in html (or robotizing the site), or some pages can be gotten in .pdf when a link on the lower left corner is present.
If anyone is willing to download the site, so far I'm halfway and got about 240MB already.
Problem is the site is not really in html format, still gives me trouble loading main page offline.
It'd be nice to be able to convert this to LRF or other formats...
Please let me know if you want to help out a bit in the conversion, or may start a conversion of your own I can help with!
*Edit: Here is a more direct link:
http://en.wikibooks.org/wiki/WB:FB *