These are the custom Drupal 7 modules in use on http://wimleers.com.
A (fairly extensive) demo of my Hierarchical Select module.
See it in action at http://wimleers.com/demo/hierarchical-select/taxonomy.
(Includes a minimal port of Jeff Beeman's "Arizona Standards" module, which is an implementation of the Hierarchical Select API that allows one to easily browse (and assign) grades of the Arizona state educational standards grading system.)