I'm not sure if anything like this has ever been done before, but it could be a neat way to get some interesting new DOFFs out there, especially some of the creative 'alien' races that people come up with. I'd love to see more unique 'alien' DOFFs!
I think it'd be a fun way to get the community involved in something they love. Of course, there would have to be some guidelines on active powers (such as non-lockbox powers only, or some such) as well as traits to keep things balanced.
Contests like this aren't totally unheard of, and as the DOFF system has stagnated a bit, this could be a way to get some insight from the community about the system and what they'd like to see, as well as infuse some interest into it.