Facets
https://www.drupal.org/project/facets/
3.x Compatible
Facets Taxonomy Multilevel
https://www.drupal.org/project/facets_taxonomy_multilevel
Working with facets 3?
Facets Pretty Paths
https://www.drupal.org/project/facets_pretty_paths
Better Exposed Filters
https://www.drupal.org/project/better_exposed_filters
Use Facets Exposed Filters submodule for BEF integration.
2.x Only
Entity Reference Facet Link
https://www.drupal.org/project/entity_reference_facet_link
Core Views Facets
https://www.drupal.org/project/core_views_facets
Other
Configurable Views Filter Block
https://www.drupal.org/project/configurable_views_filter_block
Split filters/sorts blocks for sidebar/top layout.
Taxonomy Facets
https://www.drupal.org/project/taxonomy_facets
Dynamic taxonomy listing pages.
See also: https://www.drupal.org/project/tvi
Views Ajax History
https://www.drupal.org/project/views_ajax_history
Remember facet selection?