GoodBooks.io - Largest curated collection of 8,500+ book recommendations.
DSpace - DSpace open source software enables open sharing of content that spans organizations, continents...
Goodreads - See what your friends are reading.
TinyCat - The online catalog and integrated library system for tiny libraries, powered by LibraryThing.
Read This Twice - Verified book recommendations from people we look up to
Invenio - Invenio is a free, open-source software to run a digital library or document repository on the web.