Some thoughts on mechanics I've been wanting to bring up:
1) If you're going for the brief-adventure system (which I think is a good idea, and it appears you're doing for now), why not simplify it and give out XP based on each adventure? The judges can take a look and assign it an XP total for its completion (as a general guideline, I'd say about enough XP to level up, if you were at the lowest level that could reasonably complete the adventure), then maybe give the DMs a certain amount of bonus XP to allot as they will when the adventure is done.
I've used similar systems (level by adventure, or rather by accomplishment) in home games, and it works surprisingly well. Six-week adventures, at about a level apiece, will mean it'll take at least two years real-time to reach level 20 -- maybe too fast for some peoples' tastes, but take into account that that's bare-minimum. For the more average player, who'll need some down-time between adventures, and won't always be taking on the toughest stuff they can handle (as it's hard for anyone to know for sure), that would give a good 4-5 years of time to develop a character (levelwise.) That seems like a good timeframe for these boards -- if the game lasts that long, we'll have a handful of those really accomplished players, but it's going to be a very few who are going to be able to stick with it that long.
2) I'm with reapersaurus that there's some development to be done on the world itself. Perhaps put together a map, and let people fill out regions (a limit of one per person), with some decent amount of description for the area... Individual places can be invented and incorporated into the setting on a per-adventure basis, but if you start adding full regions in this manner, you'll end up with a confusing, muddled, misshapen world pretty quickly. (*cough* Forgotten Realms *cough*)
Of course, when I say this it also means that I have my own region/culture I'd like to see incorporated into this sort of setting

Just an area about the size of Kansas, equally flat, with some monked-out nomads... And I'm sure that there are a variety of others with their own little pet Favorite Regions they've introduced into their own campaigns, that we could put together (with a little work and a lot of compromise) a reasonably realistic, fleshed-out campaign setting.
3) Also, I demand a Dwarven Pantheon, with a god of totally whooping up on everything included. One LG God (as in greyhawk) is just too bland for such a proud civilization as the Dwarves!