Lightweight JavaScript to replace select box area with intuitive easy-to-use multiple select dropdown
drupal selectize Drupal facets multiselect
rejected as too heavy (reliant on JQuery), and often not that well maintained, especially in Drupal:
Chosen Selectize Select2
Will be using TomSelect, or i guess they call it Tom Select: https://github.com/orchidjs/tom-select
Even made a Drupal module for it already, needs work though: https://drupal.org/project/tomselect