Wowio is a fun source of e-books. Their apparent business plan is interesting.
You register for an account to download e-books. So far so good.
As part of registration you are asked to fill out an optional survey of interests and reading habits. Each e-book you download is a PDF file with a few extra pages at the beginning and end. Before the e-book are pages of ads by sponsors according to your interests. After the e-book are pages from Wowio advertising similar e-books to the one you just finished reading in case you do not know what to read next.
The result is that you hit "page down" a few times to skip some ads and then have a nicely formatted e-book. The extra pages at the end are even less obtrusive since you almost instinctively close your PDF reader when you get to the end of the story.
