Two quick Unified Resource Locator that caught my eyes yesterday evening during my commute:

Sometips by Jordan Mechner about game design principles for narrative games. The second hand "List the actions the player actually performs in the game and take a cold hard look at it. Does it sound like fun?" is an interesting filter to prioritize the interactions you want your users to be engaged in. A sort of follow-up to Crawford's list of verbs I mentioned the other day
Choose Your Own Adventure (thanks Carly for this), a visualization of interactive books

Why do I blog this? both are about games/entertainment but these principles/viz can be applied to other domains. I see them as important interaction design heuristics.