Tilmann, I will try to see what I can find of smileys with a proper and useful copyright. If my initial search is any indication, then I will have to luck out and find something claiming to be a canonical smiley collection from someone like the original author.
Many, but apparently not all, of the 15x15s on the two sites mentioned are also found in vBulletin, a commercial package, though who came up with them is anyone's guess.
Animated gifs are hugely popular on sites that have them. I happen to like them too. 😊
Frank.