DSpace - DSpace open source software enables open sharing of content that spans organizations, continents...
Goodreads - See what your friends are reading.
Invenio - Invenio is a free, open-source software to run a digital library or document repository on the web.
LibraryThing - A home for your books.
Evergreen ILS - Evergreen - Open Source Library Software
Libib.com - Our library management app caters exclusively to home and private libraries.