Ok, i'm pretty new to these forums, so not sure if this'll work.
I'm starting something new, and when i think of a name for it i'll tell you 
My idea is, that i come up for an idea for a map, make textures and perhaps some sounds. Then, i post the .wad up here, with some sample architecture, along with the theme and any reference i can find.
After that, i'm taking up offers for mappers to plan the map and actually make it. You have creative freedom over what objectives/modes/numbers of players etc you want, as long as it sticks to the theme i've chosen.
Hopefully this should bring out some interesting maps, as mappers have more time to spend planning, rather than worrying about themes and the like.
This contest is running over on The Specialist forums.
There is no deadline, i decide when the submissions end.
When the creator I think has made the best map has finished his map, then the whole thing will be uploaded and ready to be downloaded and played like any normal map.
Sound fun? heres the first theme 
Idea 1: - Nineteen Eighty-Four
Based of Orson Welles' book of the same name, this map is set in an alternate version of the year 1984 on the continent of Oceania which spans the Americas, Southern Africa, Australia and England (who's name has been replaced with "Airstrip One"). The future is uncertain, the present is changeable, and the past is undeterminable. The continent of Oceania is ruled by one party, simply named The Party, which is lead by one man named Big Brother. Everyone in Oceania must love Big Brother, or face being erased off of the face of the earth. The Ministry of Truth works tirelessly to change the past, make it so that speaches, newspapers and even people have never existed by altering government records. Ever day, the entire of Oceania locks itself into the "2 Minutes Hate". This is where, on everyones Viewscreens (a permanently on TV) display pictures of the most hated men in and outside of Oceania. The citizens are encouraged to direct all the hate, jelousy, want, needs and strife towards these images through any means. Swearing, fighting, throwing things, or simply curling up and crying.
It is during the 2 minute hate that people snap. People are broken in half like eggs, to reveal the raw hate that is their yolk.
Reference:
http://www.newspeakdictionary.com/ns_frames.html - The Newspeak dictionary. (Newspeak is the official language of Oceania), a 1984 fansite.
Theme Setting:
Here are some samples of the themed corridor i've set.
[Blocked Image: http://spacer1.pwp.blueyonder.co.uk/wadpacks/1984/1984_1.jpg]
[Blocked Image: http://spacer1.pwp.blueyonder.co.uk/wadpacks/1984/1984_2.jpg]
[Blocked Image: http://spacer1.pwp.blueyonder.co.uk/wadpacks/1984/1984_3.jpg]
(note: the .wad is incomplete as of yet, so its not downloadable. will be up soon)
I'd like you to tell me what you think of the concept of this contest idea, and if you'd participate.
You're free to map away when the .wad is released.