Nice, we're getting there. A few crits for the new ones:
tocky:
I think you used an old base, because you're missing the new aa around the borders and the first one could do with some more internal smoothing as well.
Feel free to alter the colors of the second one a little more, to give more of a green tinge.
Here I think the expression would benefit greatly from single-pixel pupils, and white in the eyes to go along with the others stylewise
For the last one I have no real crits
cave:
I'm not sure if a whistling smiley even needs those pronounced inflated cheeks, most of the other smileys in this set seem to do without too elaborate shading.
Yeah, well, I can't really pick a favorite of the other.
Thanks for getting this done so fast now guys. I'll have a go at the thumbs up ones myself, if I manage to get my last homework assignment for now done today.