This module alters views' filter forms so that the drop-down or select box widgets are represented as checkboxes or radio buttons instead. This provides an improved interface when the number of choices for the filter is small.
This would probably be better solved with the views module itself, and it is a registered issue there: http://drupal.org/node/122261
But for those who want to effect a global change to all view filter forms more quickly, this module should satisfy that need.
Update 24-July-08: If you are using the Views Filterblock module, please download the current dev release of Views Checkboxes. This is because Views Filterblock provides its own form so Views Checkboxes has to modify that form as well.
It has been suggested that Better Select may be an alternative to Views Checkboxes in some cases.