I had an idea that I stole from a Mario RPG hacking community that is completely original and new.
In a small timeframe, each hacker submits a hack on a theme, for example, Chrono Christmas. Minimum hack length is a single frame (screenshot length), with no maximum.
The idea would be to get more people aware of what can be done with hacking, and hopefully get a few people to try out hacking that hadn't before.