Eelke Folmer, a professor in the Computer Science & Engineering Department at the University of Nevada, dropped me a note about his work on a pattern library for game usability & game accessibility.
You can find the two libraries at:
Some of the interesting patterns include: Freelook (giving the user freedom to look around independent of where they are currently heading), Instant Replay (allowing users to lengthen their enjoyment of a particularly exciting accomplishment, and Playground (which allows users to experiment without the fear of death.)
Freelook is just a good pattern for any web application. Let the user have freedom to explore the interface without having to directly leave the mode they are in. This could be accomplished on a web site by things as simple as lightweight tour modes (employing lightbox effects).
Instant Replay may not be as applicable to a web application but it follows the principle of letting users get the fullest enjoyment from an interface.
I think Playground definitely has its place in applications. The user needs to feel that they can experiment with their interface without the "fear of death." Which means the user should be able to experiment with the interface without getting into a mode they cannot return from (captured!) or committing a command they cannot reverse (death!) Obviously this is challenging as it requires some level of undo or intelligently placed confirmations (in contrast to idiot boxes that tell the user the obvious) preventing the user from falling off of a cliff.