i like this idea a lot, and i'm sure fluffywelshsheep will find this for us all, but i'm sure there is a more general barter site - it's not strictly barter, basically everyone offers up their services/goods/time and someone might say "i need a plumber" so a plumber will come and help you out and then someone might say "i need some garden help" so I could go and give them a hand
so it's not a direct exchange of plumbing for gardening help, more a community sharing their skills and the idea is you just give something that you can and when you need help, you jsut ask and someone will step up.
can't remember it's name for the life of me though.
i'm sure it's a good idea on paper, but will no doubt be abused.