MobMania allows to do serveral new things. Catch mobs with eggs. configure the chance of catching mobs. let mobs attack each other. let snowman's do damage. When villagers die, zombies will spawn from them. fus roh dah! riding mobs, does damage. Of course, as this is still in progress, not everything will work allright. But most will work. Click here to read more at the bukkitdev page!
Read the submission guidelines, it should be [FUN/FIX] it is also a good idea to have a picture and maybe a small changelog. Dont have time to check what your devbukkit page looks like.