Having received not a single response, I guess that I'll have to push forward on my own.
From what I've read about Calibre recipes, XML feeds appear to be important and useful. I've found three so far:
http://www.icij.org/feeds/rss/globalmuckraker.xml
http://www.icij.org/feeds/rss/projects.xml
http://www.icij.org/feeds/rss/resources.xml
It's a small start but I can see that working on this will become more involved.