What...Are...Those?
Holy crap.
Now that you mention it, though, custom smilies!? hmmmmm? I kinda like that idea, and it wouldn't really be all that complicated to implement.
Actually since in a sense your just referencing an image file and in most cases and animated gif all you really need to do is upload them to the administrative file upload tool and then you can paste the path in your post where ever you want the thing to appear. I agree it would be much nicer if there was a way to import out own custom ones though I wonder if someone would go nvtz and end up with a few gig worth of smilies on your severs.