The book I worked on for Digital in a Day was Sue Lange’s humorous science-fiction novel, The Textile Planet, available at the wonderful Book View Cafe, where you can read books and excerpts online.
The Textile Planet is available for free in the following formats at its Book View Cafe Bookshelf (the PDF listed is not my own, but a much better PDF produced by Sue Lange herself!):
Kindle/Mobipocket Sony/Epub PDF HTML Sony MS Reader
And a gallery of screenshots of the various digital formats! Note that the Kindle 2 screenshots, if you scroll to the bottom, have chapter navigation enabled.