At the AVCon which I just attended, they had an anime art competition. I think that's a great idea, and I went to the Manifest page looking for info on the same thing there.
Unfortunately it turns out the only fan art competition that seems to have been run is one to select an image for the promotional postcard, and that's long concluded!
I know it's short notice, but would there be any way to organise a fan art competition, or at least a way to contribute fan art for display at the con? I'd love to submit something myself