1. A method of controlling the shape of a peer-to-peer content distribution cloud comprising at least one tracker node and a plurality of peer nodes, said method comprising the steps of at the tracker node: (i) receiving a request from one of the peer nodes requesting information about one or more other peer nodes to connect to; (ii) accessing information about a plurality of available peer nodes associated with the tracker node; (iii) selecting one or more of the available peer nodes on the basis of one or more criteria and on the basis of the accessed information; (iv) sending information about the selected available peer nodes to the requesting peer node.