Berggren and his team designed the Readmill app so that words--and only words--are the focus point of every page. But if you find a passage you like or a sentence that irks you, you can highlight it on the page and then comment on it right from within the book. Other Readmill users reading the same book will then see these comments and can choose add their own thoughts. This starts a discussion--indeed, a bona fide social network--within the book, without ever having to leave it. The social network-in-a-book format also allows authors to take part in discussions with their readers, right inside the margins of their own book--something Berggren has found both readers and authors love. And of course, if a reader doesn’t want to see other people’s comments, they can just disable them and stick to the words at hand. - www.fastcolabs.com