In plain text format though? AFAIK, most is in PDF, EPUB or mobi format. I'd presume it's not too difficult to extract text from the latter two, but extracting

In plain text format though? AFAIK, most is in PDF, EPUB or mobi format. I'd presume it's not too difficult to extract text from the latter two, but extracting text from PDFs is far from simple, and something you get working for 1 PDF won't necessarily work on another.