Id like to see a LOST themed pin. They have alot of material to work with, the island, time travel, the hatch, good vs evil and all the different characters are there for a great pin.
Sports wise a UFC pin would be great but dont see it selling well. Music wise a TOOL pin would be my choice followed by Pink Floyd.
My 6yr old said he wants a Star Wars Force Awakens, hes probably closer to being right on whats soon from Stern