Mo' Creatures is a mod that adds a bunch of animals to Minecraft. I think it would be a cool thing to have in bukkit. http://www.minecraftforum.net/viewtopic.php?t=86929
This question has been answered too many time already. The people who made bukkit won't support mods until Notch puts out an official Modding API. So until that happens no mods that add any new block/item into the game will work with bukkit.
