Seeing all these pixel-shaped smiley, I think one thing to consider would be having different colors, depending on the smiley's mood. That would make them even more pixely in a way, though it might create visually messy posts. Or maybe using that orange-ish color from the forum's IM icons instead of the egg yolk yellow.
wow it has been for ever since i have pixeled. sorry for the lack of transparencymy god what did photobucket do to my pixels?! i'm trying to fix it so it doesn't look like a jpeg...