Pebble is a lightweight, open source, Java EE blogging tool. It's small, fast and feature-rich with unrivalled ease of installation and use. Blog content is stored as XML files on disk and served up dynamically, so there's no need to install a database.
Apache Roller is a full-featured, multi-user and group-blog server suitable for blog sites large and small. It powers internal and external employee blogs and Sun, IBM and other companies as well as the JRoller.com Java blogging community.