Come to my Secret Room
Another link from Kottke, this time to an article on secret rooms. I love the idea of secret rooms, secret passageways too. These aren't the sort of safety rooms you see in Panic Room or Hostage, but rather rooms that are just hidden behind what look like normal pieces of furniture (notably bookcases) or features (like staircases and fireplaces) and are generally just offices or dens.
Cool idea though.