For me it works on most URLs not containing a path components but sometimes it chokes. Seems to return the latest successful query then?
I think it's a very useful idea. Maybe a bookmarklet is second best to a browser plugin (but this one can surely be improved):
javascript:(function(){var%20s=encodeURIComponent(window.location.href.match(/:\/\/(.[^/]+)/)[1]);open('http://colrgrabr.swissamigos.com/?url='+s+'#'+s);})();