+1 Agreed!, we don't need a bunch of separate threads for stuff like this because then good ideas get pushed further back and less people see them and push the good ones to the top!
So heres a few things I'd like to see: Welding mask, Various suit ties, bow ties, scarves and other assorted neck accessories, Robot parts (So I can give myself just a robot arm or a robot leg), See-through jelly skin, Peg leg, inflatable parrot, eye patch, +1 for crowns of various types, and more toku-themed costumes like the one that seems to be based on ultraman :) I'd love something that looked like an awesome kamen rider or super sentai helmet.
More hair accessories. Clips, pins, hats, headbands, veils, you name it. I also love the idea of scarves and suchlike. Maybe some animal-themed clothing? Sloth and fox t-shirts would be cool!