I've just completed the Taxonomy and Metadata online course run by AIIM.
It's a very well rounded course, comprehensive and thorough. Currently only available at Practitioner level. Perhaps a Specialist level is forthcoming. It covers everything you need to know to set up a taxonomy and metadata project: how to build a business case, who to involve and how to plan it all out from beginning to end.
It also introduces the subject in a nice visual, easy to understand way and presents the 3 fundamental concepts of visualisation, relatedness and vocabulary control. It didn't however, walk you through the actual construction of a taxonomy, which was a little surprising and the sections on concept/term identification and facets could have been a little more inclusive. That said though, it's a very good course and well worth doing if this is a new area for you.
