There seem to be a lot of broken links in posts.
I just quoted and fixed one that was http://http//blah.blah.blah
I've also seen several where the link actually points to the post that the link is in (no idea how that happens, but it has happened more than once).
I don't have a design fix in mind, but there are enough problems to suggest something could be better. Maybe a clearer form? Maybe checking for a live link when the submit button is pressed? Maybe fixing some obvious format errors? Dunno.