In this poster, we present Oyster, a Peer-to-Peer system for exchanging ontology metadata among communities in the Semantic Web. Oyster exploits semantic web techniques in data representation, query formulation and query result presentation to provide an online solution for sharing ontologies, thus assisting researchers in re-using existing ontologies. Categories and Subject Descriptors H.3.4 [Information Storage and Retrieval]: Systems and Software—Information networks K.6.4 [System Management]: Centralization/decentralization General Terms Management, documentation, design, reliability Keywords Ontology, Peer-to-Peer, Repository, Metadata