Monte Cook (co-designer of 3rd Edition Dungeons & Dragons and author of the awesome Return to the Temple of Elemental Evil and Ptolus) has a cool new project out: DungeonADay.com. He's designing a megadungeon (hundreds of rooms, according to his definition) and posting them a room at a time. I've read over the preview of some of the rooms on the first level, and I have to say I'm super excited about this project. The art and maps look great, there's background and handouts for the players, and, of course, the encounters are super interesting (spoiler alert).
To get access to the full content, there's a subscription of $10 / month, with discounts for quarterly and yearly subscriptions. Personally, I have my plate full with games to run, but if I could find a DM to run this adventure for me, I'd gladly pay for the subscription.
Here's a bit form Monte's site describing the assumptions behind his design:
Whether you're playing out of the little white box, the Basic Set, 1st Edition, 2nd Edition, 3rd Edition (or 3.5), or 4th edition, dungeons come into the game. But dungeons mean different things to different people. At Dungeonaday.com, I plan on taking a rather old school approach--but even the meaning of that term varies depending on who you ask. So, I thought it valuable to share the assumptions I'm making as I design the dungeon.
These, then, are my Ten Tenets of Dungeon Design.