I agree with Adam - they do look great, and would probably work very well as parts of a sprite - I bet you could even make the guy look like he was talking if you put the right frames in the right order.
But I don't think they'd work as smilies. They'd really annoy me on a forum - I'd spend my whole time squinting at the screen trying to work out if the other posters were happy or pissed of or whatever.