I like the idea of mod awarded badges! Would give people something to aim for rather than just going to the shop and buying.
Also if we are going to add extra collectibles (and that's a big if) would it be possible to allow us to display more? Maybe add a third row? No point going to all that trouble of getting them of we can't show the off right?!
Not sure if it's already been said buuuut pokemon!
Or furniture series based on the species of villagers (alllll of themmmmm)
Adventure time themed furniture!