Omeka is a free, flexible, and open source web-publishing platform for the display of library, museum, archives, and scholarly collections and exhibitions. Its five-minute setup makes launching an online archive or exhibition as easy as launching a blog.
The Interaction Consortium is building a free, open source web framework specifically for the GLAM (Galleries, Libraries, Archives and Museums) sector. It's called GLAMkit, and it is based on the leading-edge web framework Django, and has out-of-the-box support for public events, exhibitions, visitor info, social media, and hooks for collections, ecommerce, ticketing, and so on.
R. Loverance. CULTURAL HERITAGE on line: the challenge of accessibility and preservation. International Conference Firenze, 14th-16th December 2006, page 232--239. Foundation Rinascimento Digitale, (2006)