I have a blog where I write in French, and sometimes in English. Right now, the distinction is made with a "tag" called "In English", so that users can get the feed for, say, only the English posts.
In the new version of my blog, I would like to be able to have posts in whatever language, and (that's where I'm stuck) have a simple way for users to choose which language(s) they want to see/follow via RSS. Also, the same post can be available in different languages (translations)
I code everything myself, using the Symfony framework, so I can do whichever UI I choose.