There's a likelihood this has been done before but I'm just so excited for the upcoming Thor film and let's do this contest based on that.
Simply make an "End of the World" scenario with, of course, superhero/es in them. You can have the battle of Ragnarok as the title implies. You can have superheroes saving people from a global destruction. You can even make a Judeo-Christian end of the world theme with the final battle of good vs evil. DC, Marvel, Image, Valiant, whatever. Go crazy. Anything that shows "the end times" can work. Just make sure you got superheroes in them m'kay?
Edit: Since it has no entries, deadline is set to the 25th of March. If no entry til then then we can scrap the contest. Hehehehehe!