TinyCat - The online catalog and integrated library system for tiny libraries, powered by LibraryThing.
Ambra - Ambra is an innovative Open Source platform for publishing Open Access research articles.
DSpace - DSpace open source software enables open sharing of content that spans organizations, continents...
Keepy - Organize & Save your kids' artwork, schoolwork and mementos
Invenio - Invenio is a free, open-source software to run a digital library or document repository on the web.
Trello - Infinitely flexible. Incredibly easy to use. Great mobile apps. It's free. Trello keeps track of everything, from the big picture to the minute details.