A really great list of features that game designers shouldn't take for granted.
From Business Week:
Steve Krug argues in his book Don't Make Me Think! that a good program or product should let users accomplish their intended tasks as easily and directly as possible. The less time it takes a person to complete a desired task (even if only by a few seconds), the more satisfying it becomes. When that happens, people are more likely to use a product in greater frequency and return for more. So in the spirit of improved usability, here are ten standard features every videogame designer should embrace.