You may also want to consider SLA (formerly called Special Libraries Association--www.sla.org). The divisions (like SIGs) you might be interested in include Biomedical and Life Sciences, Pharmaceutical and Health Technology, and Knowledge Management. SLA also has geographic Chapters. For a somewhat heavier research orientation (IMHO), there's the American Society for Information Science and Technology (ASIS&T--www.asist.org). Both see "tagging" as categorization with controlled vocabs.