If you like historical fiction, you may wish to check out this site:
http://altsheler.woodwardworks.com/
The ebooks are nicely formatted and consistent with similar covers within each series.
Here's a breakdown:
The French & Indian War Series (6 vol.)
The Young Trailers Series (8 vol.)
The Great West Series (2 vol.)
The Civil War Series (8 vol.)
The World War Series (3 vol.)
The Texan Series (3 vol.)
19th Century Novels 6 vol.)
20th Century Novels (13 vol.)
21st Century Novel (1 vol. - if my memory is correct)
Short Stories & Miscellany (2 vol. - if my memory is correct)
If you like a bargain, you can't beat this.
Don