In the corridors of time, I've heard of such a smiley, but sometimes words speak louder than pictures. Read dear debbiejo's posts and you should find a 'word painting' that is representative of what you are looking for.
Obviously, this was your point all along, but redundency is something I'm getting rather fond of.
The last word in a thread usually means that nobody cared anymore. You basically have to assume on your own that everybody felt you got it right (as if it's some kind of conclusion to the thread) but it just doesn't work like that on messageboards.
To assume it in any case still is quite a bad idea though..
(now please let someone post after me because I feel too holy to be contradicting myself now with my 'last word' view)