This is a bit late, but-- Worldwide Adventure Writing Month! It's awesome! Tell your friends!
I haven't quite decided that I'm going to do it, on account of having a lot of stuff that is to be happening this month. But, most of it is in the first half, and then I'll have a lot of (hypothetical) free time.
I've done National Novel Writing Month, so part of me says I should do it just on that account. So I can say I've done both, and because it can't be any harder. I hope.
I'm thinking that my somewhat misreading of Keep on the Borderlands might not be a bad place to start. Also, something desert themed. Probably do D&D, or maybe possibly d20 Modern/Future, because I have a decent idea of what works in those systems.
Not that I have any idea how to write an adventure. I've never actually run a published adventure, if you don't count three hours worth of Nightfang Spire which I subsequently abandoned because it was weird and incomprehensible and really not what anyone in the group was looking for. I've run a couple of decent campaigns, but I've never run anything remotely approximating an adventure, because it's unusual for me to work in such episodic terms.
Which is, oddly enough, why I think I should do this WoAdWriMo thing. Because I've never done anything much like it, and I don't think I'd be likely to for any reason other than a defined event like this.