Free classics are available here on MobileRead in most of the various formats. Go to
this link and click on "html" (next to "full list") in the upper right section. That will give you a list of all 22,000 some books currently available for download. The quality tends to be very good here, often complete with illustrations. Download Calibre (also supported here by the developers) and you can convert free classics from and too whatever format you need.