I came across a parade that was done at Dragon-Con
http://www.youtube.com/watch?v=ZoJ4rzAQ1Wk
Looks pretty awesome... but i think with the gun laws in California we'd be arrested for doing that :[
It is probably unlikely that Fanime will be able to get anything like this done in the next few years. You know, parades disrupt traffic easily. Maybe in the future if/when Fanime becomes bigger and can warrant a reason for such a thing, but again, I doubt it.