We present an architecture for combining wikis containing hypertext with ontologies containing formal, structured information. A web-based ontology editor that supports collaborative work through versioning, transactions and management of simultaneous modifications is used for ontology evolution. In wiki pages, ontology information can be used to render dynamic content and answer user queries. Furthermore, query templates are introduced that simplify the use of queries for inexperienced users. The architecture allows easy integration with existing ontology frameworks and wiki engines. The usefulness of the approach is demonstrated by a prototypical implementation as well as a small case study.