Loudblog is another of my favourites. It's easy to use, quick and simple to setup, and very stylish. You can post text comments (blog), in which presumably you can include images; videos; and audio files. The software comes with a very cool embedded flash player for playing the media files. All of your posts are categorised and each category has its own RSS feed, as does your site as a whole.

The creators of the software encourage modifications to the code as well as the use of custom-made plugins, hacks and templates. The community is therefore encouraged and there is a small forum on the Loudblog homepage.

Podcastamatic is an open source, Perl-based web application enabling you to distribute your music. "Podcastamatic automates the creation of a webpage and a RSS feed for your podcast, based on MP3 tags. A webpage can either be automatically generated from scratch or generated from a template you create." The system can work with MP4 files as well as MP3 and iTunes tags are also supported (even including images). There are Podcastamatic forums too.

Note: the above link doesn't seem to be working at the moment, see my comment for an alternative download location.