I love taking pictures of completely random cosplayers doing completely random stuff. Last weekend at Sakuracon, I saw 5 people all walking by at the same time, and that made up a Rock Band with their props.
With so many cosplayers, just think of the most creative or crazy stuff they can do in one picture and snap it! On the last day, people could submit like their 2 or 3 best con pics in a contest to see who's was most ..... interesting, to say the least.
It's the spirit of cosplay! ^^