Business directory based on folksonomy

I am currently working on www.HotFrog.com.au that uses folksonomy ideas to overcome some interesting business problems.
Obviously using a folksonomy overcomes cost in creating/managing taxonomies also gives you the benefit of being more keyword rich with helps with SEO.
Another business problem I had was the merging of taxonomies. I had to merge a couple of directories into one but did not want to bear the cost of mapping between the taxonomies. Also the taxonomies had different level of detail so one categorised down to pumps and the other categorised down to 'centrifugal pumps'. I used the category descriptions of the original directories to form the tags in HotFrog and the outcome was very effective. I have had some tag cleanup tasks to do but the effort is a lot less than mapping etc. In fact I had a usable merged directory within 10 mins of effort.
Creating a ‘hierarchy’ or related tags for the directory was easy as you query the most frequent tags for companies that share the same tag as this one. For example http://www.hotfrog.com.au/Products/Condiments has related tags of Chutneys, Dipping Sauces, Fats & Oils, Food, Jams, Mustards, Pasta & Pasta Sauce, Relish, Sauces, and Seasoning. The related tags seems to be giving better results than our previous managed taxonomies for company directories because it has returned interesting related products/services that you would not logically link but are relevant to the users. There is still some tidying up to do but have a look around and see what you think.
Using tags instead of a managed taxonomy in hotfrog was suitable because breadth of information was more important than cleanness of data and categorisation.