In reply to caseyfather: Not got into it - YET. I've registered after my friend told me in great detail what he has found and where and told me that I MUST try it. One for a rainy day I think. There is a 6 mile walk around my village that has 10 of them. I just have to get out and find them.
It looks like an excellent excuse for people who don't just go out and walk to just go out and walk.