- Nook e-ink: PDF, EPUB, PDB and Nook's own format
- Nook Color: PDF, EPUB, DOC, text.
- Sony Reader: BBeB Book (LRF), PDF, TXT, RTF, EPUB
- Kindles: PDF, Mobipocket and Kindle's own format
- Pandigital Novel: EPUB and PDF
- Kobo: PDF, EPUB, txt
Munseys offers 20,000 titles in 12 formats. The proper choice for Kindles, Nooks and Sony Readers are explicitly identified. Titles can be found by searching author, title or tags. Lots of books have tags, most don’t. You can also browse by category. To find the categories when you are on the main page, scroll down to a red box with 39 categories. Munseys’ e-book collection has many titles found in the other collections below. However, the “pulp fiction” and “orient express” seem unique to me. Tip: When downloading a title, first click “Select One” to choose the desired format, then click “download.”
Palimpsest Online provides high-quality pdf titles by over 70 authors. Titles are mostly European and American serious novels, but also include the King James Bible, plays, poetry, fables, epic sagas, philosophy and histories. Extensive collection of P.G. Wodehouse titles. The numbers "6X9" refers to 6 inches by 9 inches. The other size is "3X5" for 3 inches by 5 inches.
Feedbooks provides high-quality titles in a variety of formats: EPUB, PDF, MobiPocket/Kindle. This site contains: Public domain classic fiction and nonfiction titles can be browsed by 30 categories or 600 authors; and titles by new authors.
Manybooks provides thousands of Project Gutenberg ebooks in dozens of formats including PDF, EPUB, Kindle, Sony Reader, etc. The site offers search, advanced searching and browsing by author, title and over 60 genres.
PDFBooks offers classics and unpublished fiction and nonfiction in pdf format. Titles can be searched or browsed by author. The Web page for each title gives a description and table of contents.
DigitalBookIndex offers an extensive list of nonfiction in PDF, EPUB and even Kindle formats mixed with Web books and even some subscription titles. Search by author or title or browse by subject. Contains a special American studies section.
eBooks Directory has over 4,000 PDF titles divided into over 400 categories. Most of these eBooks are new.
Globusz offers lots of old and new eBooks. eBooks can be read online or downloaded in txt format. Access to older eBooks is through 20 categories and a list of authors in the center of the page. Access to newer eBooks is through a list of featured authors on the left side bar.
Online Books Page is one of the largest of these indexes. Titles can be searched by author and title and browsed by subjects, which is actually browsing by Library of Congress call number or subject term. Since this is an index of other archives including all the ones listed below, the format of the content varies from txt and pdf to html Web pages. The index and archives page is the most comprehensive list of etext archives I know.
Internet Archive is probably the second largest index of ebooks. This archive offers simple and advanced searching, but no browsing capabilities. Each title has a unique page offering complete title, author and publisher information, a description of the content, and, on the left-side of the page, links to the variety for formats available for the title. Other areas of this index include "moving images," audio recordings, and software. This archive is unfortunately including the growing number of Google Books.
Project Gutenberg is an index and an archive actively collecting texts produced by volunteers. The index can be searched and browsed by author or title. Volunteers have created "bookshelves" with lists of titles in categories they define, e.g., "best books ever" and "precursors of science fiction." Advanced searched allows narrowing by format, e.g. epub.
Best World Free Digital Libraries is a list of digital libraries in the world.