The first generation of peer-to-peer file sharing systems followed the traditional client-server paradigm. However, legality and scalability issues have driven the development of decentralized file sharing protocols; the most popular of these being Gnutella. To date, such systems have been unable to match the Quality of Service (Qos) offered by centralized architectures. AGnuS improves QoS on Gnutella by increasing file availability, improving network friendliness and increasing file quality. This is achieved by layering caching, load balancing, content-based routing and filtering services on top of the core Gnutella protocol.