On Difficulty Levels
Daniel Boutros writes an article about how to properly implement difficulty levels in games, nothing revolutionary but a solid summary of some things to think about when adjusting the difficulty of a game.
I am personally past the point where I would willingly choose to play a game on a harder setting for no reward other than the knowledge that I beat it (with some exceptions), but providing a difficulty setting is really the least you can do to broaden a game’s target audience.