What about ad-hoc collaborative gardening/crop sharing? Skill sharing, car pooling and generally anything that fosters real community would do well I should imagine.
My wife has been trying to get something going in our neck of the woods: [foodmake.org](http://www.foodmake.org/), and it seems to be going pretty well. The goal is to get people talking and then get them off the web and connecting in the real world as soon as possible.
i think there are many car pooling websites out there already. But skill sharing would be cool; post/barter your skills. I can only think of craigslist as a good place to barter your skills