I agree with the challenge point; mostly in the challenges I make things and learn things I have not tried before.

Another character idea would be to take a sound clip and make a character that says it or does something in time to a piece of music. Everyone gets the same clip or piece of music but has free range on a character. That then helps people who think making a whole person in a month might be a bit tough as one could create something more simple as long as it delivered it's message.