At Comikaze I saw the girl from those "Sun Drop" soda commercials. I'm not sure if she was a cosplayer or the actual actress though. ^^; (Sun Drop was one of the sponsors/booths there, so...)
I also saw someone dressed as Psy, but also wearing a Gundam head. (Oppa "Gundam" style!) He had the song coming out of some portable speakers as well. XD
And my little neighbor dressed up as Michael Jackson a couple of years ago. People tend to dress as whoever's big in the news/media lately- Presidential candidates, Snooki, Octomom, the UFO kid (or whatever they referred to him as, I forget)...
As for myself, I'm not sure- It would be kinda cool to dress as David Bowie, I think.