Jen of Epbot went to MegaCon, a geek convention in Orlando. It was attended by fully 75,000 people, many of whom dressed for the occasion. Jen took a lot of photos of the cosplayers, including this lady dressed as the Death Star. Her hair clip is a LEGO TIE fighter.
You can see many more photos of the costumes here, including those inspired by My Little Pony, He-Man, and Doctor Who.
Regarding the other pictures, if I used a wheelchair, I would so go as Cpt. Pike or Davros. I've never seen those.