I was never especially good at doing tricks on my bike, but I always enjoyed trying. I think this video is amazing...
Another New York Time's article I found interesting. Points out some of the effects of sitting on a couch or at a desk for long periods, even if you exercise regularly.
And finally, a good list of ways to improve your running economy. I like all the points, but I'm an especially big believer in the "Get Centered" idea.
