I'm using Views' "expose filters as a block" functionality in a custom search page. One of the filters is for content type, and users need to be able to select multiple options. Views can only generate multi-select lists as dropdowns, however, and the designs require checkboxes. Using a hook_form_alter to flip the #type from 'select' to 'checkboxes' fails because the form API structures those so differently. The views_filter_pack module claims to be able to convert from one to the other, but is extremely over-engineered for this purpose. Some searching around showed that other people had the same problem but no solutions seemed to work.

Then it dawned on me that I didn't need Drupal or Views to use checkboxes, I just needed the browser output to be rendered as checkboxes.