The have. It's called the Liberty Forum. Click on one of the links and see for yourself. Lots of anarchists and anti-American posters there. I don't think this is what the forum founders wanted,but they were determined to have a totally "free-speech" site,so that's what they ended up with.
I think this is fair to say as true. I received an invitation to make posts in a libertarian-leaning forum. That is what it was for a while. Now every other post is about the Jews it seems.
I do not blame Free Republic. LF and FR are their own sites, but it is a testament to FR's popularity that it has enough enemies to swamp our little site. :\