Abstract: Finding relevant information is one of the biggest problems that Web users experience. This article describes Pharos, a new service that has been developped to help groups of Web users share their knowledge about interesting documents. Pharos relies on a collaborative infrastructure which allows user groups to index and evaluate documents on specific topics. This informati- on, possibly subjective, is synthesized to produce personalized recommendation- s. Scalability is handled by distributing servers and replicating their databases. Pharos has been implemented in Java and is currently being evaluated.