Open Friday: Deviant Settings

Clearly, my personal preference is for homebrew settings over prepackaged ones, but not everyone shares that preference. What really interests me right now are campaigns based on an existing setting that deviated from the published version of it in some way. So, for all of you out there who have used a setting written or inspired by someone else, I'd love some concrete examples of how you changed the setting through play, especially if those changes made the setting quite different than the one on which it was based.