An excursion into fixie-land is on my short list of projects. I'm hoping that it would be beneficial to my technique. I've done the "stay-in-one-gear" thing but it's too easy to coast; you have no choice with a fixie. I'd rather build something up from a frame, but I'm not married to that idea.

I'd be interested in your experiences in riding the darned things! (Is it difficult to stop/start, did you forget that you didn't have a freehub, etc.)