Any ideas?

This is called faceted search (http://en.wikipedia.org/wiki/Faceted_browser). Here is a list of possible vendors that will add it: http://en.wikipedia.org/wiki/Li...nterprise_Search_Vendors. Expect to pay $1K-$50K for a commercial product before integration. At the high end, there will be advanced features such as behavior analysis and search prediction.

Alex - Very nice implementation. It is super easy to use. But I wonder if "[x]" is the equivalent of technical jargon. I know what it means without thinking, but I wonder if Bob the new secretary does. I think I would have used a word like "Remove".

Andy - Thank you for the suggestion. I will see to it that it is implemented in some fashion.

Aaron - With a catalog of over 45,000+ active products and over 400 categories, performance did become an issue, but as you can see, with some work, we were able to overcome it. The reason for not allowing a multi-select type option is simply due to the style of navigation this is. It is a drill down or filter search. We have a "power-search" multi-select search function built into another website that would allow you to pick many criteria at once, including multiple of the same attribute. Also, the customer wanted it this way!