This site has already been proposed once, but I note the thread is rather short so I am nominating it myself under a new Thread.
Have a look at "Guardians of the Frontier":http://www.obsidianportal.com/campaigns/guardians-of-the-frontier and I think you will agree that this OLD SKOOL (remember THAC0?) D&D adventure has everything that Obsidian Portal knows and loves. It has great imagery. Even the Main Wiki Page is an artwork in itself, there is good background detail and a rich history against which the players or "Guardians" are positioned. DM Jayph's PBP game needs our support to limit the evil Illithid threat, and if that is not a good enough reason to award CotM, I don't know what is... Have a look and a read. I'm sure many fellow "OPiates" will agree.
"Shimring - The Faces of Divinity":http://www.obsidianportal.com/campaigns/shimring
(a multiplanar 3.5 D&D campaign)
"I met a traveller from an antique land....."
CotM May 2016: Mysteria: set in Wolfgang Baur’s MIDGARD.
Previous CotM Aug 2012: Shimring: High Level Multiplanar Campaign
Inner Council Member