The concept of superpeer has been introduced to improve the performance of popular file-sharing applications. A super-peer is a node in a P2P network that operates as a server for a set of clients, and as an equal w.r.t. other super-peers. By exploiting heterogeneity, the superpeer paradigm allows P2P networks to run more efficiently, without compromising their decentralized nature. This paper describes SG-1, a novel generic mechanism for the construction and the maintenance of overlay topologies based on superpeers. SG-1 is based on the well-known gossip paradigm, with nodes exchanging information with randomly selected peers and re-arranging the topology according to the requirements of the particular P2P application. The resulting protocol is extremely efficient and robust, capable to deal with a continuous flow of nodes joining and leaving the system, as well as to repair a network where up to 100% of the existing super-peers have been removed.