OpenKM is a multi-platform application for document management based on GWT, JBoss, and Jackrabbit (the content repository API).
Version 2.0 has been released, which you can test drive to see the application-style interface. The new features in 2.0 include: the previsualization of multimedia elements as images and videos, an improved an rewritten administration interface, a centralized management of templates, an exclusive area to allow users to store their private documentation, a tool for massive import and output data from ZIP files, searches by date ranks as well as translations to more languages.
However, one of the more relevant functions to mention is the indexing of the most common types of files: text, Office, Office 2007, OpenOffice, PDF, HTML, XML, MP3, JPEG, etc.
Original Article: http://feeds.feedburner.com/~r/ajaxian/~3/288781416/openkm-open-source-document-management