Give and you shall receive(a postcard)
I recently came across the site Postcrossing. The idea is to sign up, when you are then given a random address to which to mail a postcard. Your own address will then be made available so that you too can receive a postcard from some random person in the World. A very simple, cool idea. I love these simple ideas whose sole purpose is to bring a few smiles 
Postcrossing got its name as it is based on BookCrossing, another lovely idea. You leave books you have read in public places for people to find and read. I did this a while ago and was pleasantly surprised to find it had a worldwide following.
