There's something about going out for a walk that stimulates GoodIdeas. Why is that?
Also see: http://www.innovationtools.com/Articles/ArticleDetails.asp?id=9
One of the themes is based on the idea that, years ago, it took a long time to travel from place to place - by train, bus or stagecoach, or even by foot. People had plenty of time to "stare out the window" during travel time, which probably led to that a-ha rich alpha state of mind...