I think that we should have a check box in the game that we can click on to choose if we want animals to naturally spawn or not, it's just really irritating having animals or any mob just randomly spawning in my castles and other structures, then when I kill them I have to take up space on my bar with their meat.
My Suggestions:
http://www.minecraftforum.net/forums/minecraft-discussion/suggestions/2488679-custom-music-disc