I've been casting around for some software that can help me do my keywording (which is so boring!!). I recently found a product that I think might be of interest. It's a new Windows tool called Image Keyworder (Image Keyworder). It comes with a thesaurus which I found really useful because you can click on a term and it automatically adds synonyms and singulars and plurals and it has some useful batch and template functions. Worth checking out.