What about running? I have to be the most creative person alive.
It would be interesting to see a scientific study done on it.
I'd like to get a (passive) treadmill desk at some point for these reasons. I don't think I've ever found myself to be particularly creative on runs. I think I treat it too seriously, and when I'm not too serious, then I'm trying to be meditative with it or listening to nature. Interesting to hear other people's experiences.