1) using a custom "channel", which seems to rely on FB.init 2) using iframe for 'like' instead of fbml 3) htaccess or similar redirecting URLs with fb_xd_fragment in them to remove the parameter 4) filtering stats hits from the likes of Google Analytics on the basis of the URL parameter.
Here are my problems with these:
1 - well I don't use FB.init, and don't have an 'app ID' which seems to be mandatory. And I'm not tying my sites further into Facebook to solve their problem. 2 - maybe but the fbml version is quite a lot better. 3 - I have already done this, and URLs with the fb_xd_fragment parameter in them definitely 301 to the naked URLs. However, Google Analytics is still recording large numbers of hits for those URLs! I have no idea how or why this is. Something to do with the way Facebook works...? 4 - As far as I can see this only hides the problem by merging invalid hits with real ones, so is counterproductive.