Catkin is blogging tool. It will help you maintain a weblog or journal site. Features include a web interface, threaded comments and a flexible templating system. It is written in Perl and runs on the webserver.
Catkin is currently at an early stage in its development. I wouldn't encourage people to use it unless they are familiar with Perl and CGI and are willing to deal with bugs and changing file formats as the system matures.
There is a test site for Catkin. This is where I test out the code that I'm working on, so sometimes things are broken and sometimes it has features that aren't yet in the latest release. You're welcome to mess around with this site, post stories and comments, etc. The password is "password".
For an example of a real site using Catkin see Words by c.z.robertson.