The Society of Torch, Pole, and Rope) Stonehell dungeon (which is actually a composite of two-page dungeons). The One-Page Dungeon approach is a great way to design a dungeon and I have used it quite a bit myself. The One-Page Dungeon template (by Michael at ChicagoWiz's RPG Blog) is a great way to get a playable dungeon area created, as it enforces the discipline of not creating too much extraneous material that either becomes a time suck (if you are a perfectionist) or simply won't be used in play.
You can see the key posts by Dave (Sham's Grog & Blog) here and here. Michael (ChicagoWiz's RPG Blog) had an important post in between Dave's two posts, which you can find here. Michael Curtis (The Society of Torch, Pole, and Rope) wraps up this class of Hall of Fame inductees with his post on the same topic here.