STAMPS is a little program. It can run on your Mobile phone. Using this program you can see a map of the place where you are, visualised on the screen of your mobile. There, you can write a kind of SMS and attach it to the map so that other friends can see your message appearing on their map. You can write for instance: “this is my preferite pizzeria!”, to offer advice to your buddies. All the messages left in the system say something about the city where you live: what are the sport locations, the place to eat, the meeting spots. After a while, we want to use all these information to help the users to navigate the city. You can ask the system, for instance: “where is a pizzeria near by?”, and the system will search for other people’s messages which refer to the term pizzeria to give you an advice.