HERE - you can download the cataloug in either MOBI (Kindle) or ePub(Sony and other readers) and then browse through the thousands of public domain titles from Project Guttenberg, select those you are interested in and bingo you've got the eBook.
I've been using the Magic Catalogue for a week or so now and have added over a thousand titles to my Kindle library.
Project Gutenberg (PG) is a volunteer effort to digitize and archive cultural works, to "encourage the creation and distribution of eBooks." Founded in 1971 by Michael S. Hart, it is the oldest digital library. Most of the items in its collection are the full texts of public domain books. The project tries to make these as free as possible, in long-lasting, open formats that can be used on almost any computer. As of November 2010[update], Project Gutenberg claimed over 34,000 items in its collection. Project Gutenberg is affiliated with many projects that are independent organizations which share the same ideals, and have been given permission to use the Project Gutenberg trademark.