MythTV plugins exist to extend functionality to MythTV. The core Myth setup handles video, and playback capabilities for all supported media types, plus networking framework capabilities, and protocol handlers. So, without plugins, you can record and playback captured video, playback DVD’s, and playback video containers.
It does not provide an interface manage audio files as a music player, so there is a music plugin. It doesn’t provide specific News aggregation services, or weather aggregation services, so there are plugins to handle those. There are quite a few plugins, but the working set is still somewhat small.
The problem here is that plugin creation is not well documented. It’s also complicated, as it requires a knowledge of MythTV internals (including using libmyth which is somewhat new), programming for QT, and fairly strong C++ abilities. The combination of these things makes it difficult to just write a plugin for some need.
What I would like to see is two things. The first would be for Myth to improve their documentation. It would be nice to be able to have doxygen generated documentation to follow to understand how the RSSManager works for instance, as this is probably something a lot of plugins might use. Or, better handling of documentation for libmyth, which is critical for plugin creation. Basically, it shouldn’t be magic.