I made a simple plugin for a specific use-case to create documents from youtube feed items, which you can see here:
https://github.com/Komodo/komodo-website/tree/master/plugins/youtubefeed
It works semi-well but has some bugs. I'd love to have this functionality a bit more abstracted in a plugin like docpad-plugin-feedr though, basically all it's missing is the ability to create a document from a feed item.