Peter's blog consistently offers up great content, most of which revolves around megadungeon design and play. His Megadungeon Play Relections - The Immediate and the Cumulative is my personal favorite. It is elegant in its simplicity--the post primarily consists of two lists ("Immediate" and "Cumulative"). What I like is that it is a descriptive post about megadungeon play, as opposed to an armchair prescriptive post. Rather than speculate about megadungeon play, he describes it. And in the act of description, he lays the ground work for how to have a well-designed and well-run megadungeon campaign.