D3 Tips and Tricks manual available on Leanpub.
The content is almost identical, but the format is significantly different since it is written and converted from markdown into pdf, epub and mobi formats (full disclosure, I haven't tried the epub / mobi versions).
The attraction is the service that Leanpub provide. They convert and host the book and when there are additions or revisions, they make them available to readers.
What's in it for you?
Well, the price is still free :-), but if you find the content useful and want to support anyone, please consider contributing 50 cents which will go to Leanpub as a flat fee that they have when a book is sold.
I think the format is superior. While I had more control using LibreOffice and exporting as a pdf, Leanpub provides a more consistent look / feel that is cleaner IMHO. You be the judge and feel free to let me know.
You can get to the new version of the book from the downloads page or directly from Leanpub if you like.