Halloween things? :3 That's what I'm about to be doing with sculpey and it seems like it has lots of choices and would be fun
Halloween things has already been said, but I think little jack-o-lanterns and skulls would be adorable. Assuming you intend to make charms (which is quite an assumption) people also seem to quite taken with 'adorable food', for some reason or another. Or maybe try an octopus. They seem to be full of slimy goodness. XD
MANATEES! YESSSSS! And seals maybe. And ghosties? :3 Geese too! And hey, when you're finished making them, post 'em!
DO POKEMONZ. Like a Buizel! Or... Happiny. XD