Effective information retrieval is important not only for its own sake but also for improving our understanding and allowing us to evolve our information into knowledge and wisdom, and thus to stimulate our creativity and enhance our culture. Classification enables us to discover those items that are about the subjects in which we are interested, but for greater effectiveness we must harness the power of communitydeveloped folksonomies in alliance with formal taxonomies. This paper discusses experiments aimed at realizing such an alliance. Categories and Subject Descriptors H.5.3 [Group and Organization Interfaces] General Terms Keywords Information retrieval, classification, taxonomy, folksonomy, usability.