Lots of good stuff in this free book from Barbara Fister. "This lightly-edited, open access,, creative-commons-licensed collection of essays is drawn from the Library Babel Fish blog at Inside Higher Ed with additional material exploring online reading communities, mostly published at my personal blog" Dip in, share and discuss.
On the page linked below there is also a neat timeline of online reading communities.
Fister, B. (2015). Babel Fish bouillabaise. St Peter, MN: Gazornum. http://barbarafister.com/bouillabaisse.html Photo by Sheila Webber: sea (you might just see a fish), Dubrovnik, October 2014