I have a client that needs some complex matching and searching functionality. He would like us to generate search results and allow him to filter them using parallel filters like Kayak.com does. Basically, we analyze the data, come up with filter criteria and put them on the page with sliders, checkboxes and the like. The user chooses what they want to see and we filter automatically when they add or remove a filter criteria.

Kayak.com is not the only site with this type of functionality. Many stores use it in their ECommerce sites, for example. PriceGRabber and Ebay use it too.

My question is this: Is there a widget, module, library, template, whatever that I can download (free or $$$) that would give a leg up on this type of functionality?

Thanks in advance