There are also authors how publish their own ebooks without a publishing company and/or Amazon in the middle, so they get close to 100% of the books.
And there's software to turn PC, mobiles, PDA, etc into ebook readers, although those may not read Amazon's format.
I have recently experimented with the .epub and the .mobi format, it's quite interesting what one can do and how the outcome of a conversion to those formats is very dependent on the source used. PDF did rather badly, but the original file format worked quite well.
