After a mail from Rod Begbie I’ve finally decided to move to a free, open-source aggregator which actually has active development: Gregarius. Sorry FeedOnFeeds.
My FeedOnFeeds database contains around 30,000 posts – is it worth importing them into Gregarius? That’s a whole lot of content, some of which may disappear from the web in the future, and possibly available for some kind of analysis.
I’ll have a few FoF customisations to port to Gregarius plugins, but a lot of them are now core features in Gregarius or already available as plugins.
I tried ripping the parser out liferea at one point. It is written in C, but it might be place to start.
Hm, the parsers do seem to be separate according to http://svn.sourceforge.net/viewcvs.cgi/liferea/trunk/liferea/src/parsers/