Blog
Blog is an interface for managing a multi-topic blog (Web journal). Its easy interface allows users to quickly create journals with several topics, all of which are concurrently accessible.

Blogunity
Community based blogging software. Uncomplex easy one minute installation routine. Easily deployable on any j2ee compliant application- and web servers. Provides support for 16 well known database-engines. Offers freely configurable number of individual/communtiy blogs per user. Simple but powerful editing of blog-articles using wiki-syntax.

Blojsom
A lightweight blog package written in Java that is inspired by blosxom. blojsom aims to retain the simplicity in design of its Perl-based "relative" while adding user flexibility in areas such as the flavors, templating, plugins, and the ability to run a multi-user blog with a single blojsom installation.

JSP Blog
JSP Blog is a Weblog written in pure JSP, built with Tomcat and MySQL.

MapleBlog
MapleBlog is a simple MVC Struts 1.1-based Web log that uses Hibernate as its model layer and Tiles/JSP for its View.

Pebble
Pebble is a lightweight, open source, blogger that is written as a web application to run inside J2EE web containers using standards-based technologies such as JSP, servlets, filters, JSP custom tags, JSTL and JAXP. Running as a web application in any JSP 1.2/Servlet 2.3 compatible web container, Pebble maintains blog entries as XML files and serves up blog content dynamically.

Roller Weblogger
A server-based weblogging software and a web application that is designed to support multiple simultaneous weblog users and visitors. Roller supports all of the latest-and-greatest weblogging features such as comments, WYSIWYG HTML editing, page templates, RSS syndication, trackback, blogroll management, and provides an XML-RPC interface for blogging clients such as w:bloggar and nntp//rss.

SnipSnap
SnipSnap is a free and easy to install weblog and wiki tool written in Java.