Oooh, I can't wait for 37 Signals to continue to explain this one. Since my buddies started working in agile teams I've been trying to interpret some of their new techniques in my creative environment.
About six months ago I started experimenting with the technique of breaking down my programming tasks into little stories. These absolutely non-technical simple one liners were to explain and interpret my work back to those who had assigned me those tasks. While at first these have been "agreement" documents. I think there is an understanding that these can be written from the start to help build an understanding of what our projects are going to be from the outset.
While I'm certain that I'm executing any strict agile methodology here, I believe that this technique is building a nice bridge between creative thinkers, grossly non-technical account managers and me - the programmery type guy. Most importantly though, people are happy. I can still design and estimate well against these stories and I have evidence about the initial application idea when designers 'create' or 'evolve' a concept with additional 'features'.