http://www.archive.org/index.php

If you go to the above link, click on Texts, and enter 'chess' in the search field, you will get links to classic books by Capablanca and Lasker, among others, that are apparently public domain.  They're pretty much all in English notation, and some scanned diagrams are tough to read; but it's quite a nice batch of stuff, ready for download.  Enjoy!

They only have about 50 chess books...

That are old...