Taxonomies Filter Widget is a robust but powerful WordPress plugin that creates a widget which acts as a filter for your categories, tags, taxonomies and numerical custom fields. Visitors will then be able to do faceted searches on your site to filter posts and pages by taxonomies and numerical custom fields, using drop-downs, checkboxes, radio buttons, multiselect and range sliders. While built especially for sites with a variety of categories, custom taxonomies and custom posts (eg: shops, directories, tutorials, job boards or listings), this plugin will also do a great job at filtering the WordPress posts and pages by categories, tags and even post format. Check a video demonstration here or use the live preview to see it in action.