[Plugin: Faceted Search] live ajax sorting of custom taxonomies for a custom post-type

Yes, this looks like something faceted search could have solved. Too bad the question expired. Thanks for the heads up though. Also, I’ve never seen that site, so it’s good to know that’s there.

Just gotta submit an ajax request on any onchange event for your checkboxes, then update the content area with your results. You could use my plugin as the backend, just submit the form through an asynchronous post, and extract the needed response html. That’s about as deep as I’m going to go into this problem, as my time is limited, but hopefully it gives you an overview of a solution.