Saving custom fields to a custom taxonomy

Question

I am trying to create a custom field for a custom taxonomy. update_post_meta works great with posts. Taxonomies are not posts so this won't work.

<?php update_post_meta($post_id, $meta_key, $meta_value, $prev_value); ?> 

How would I save a custom field within a custom taxonomy? Other solutions include the options_table (bad!) or creating a custom table (cumbersome). Is there another, canned solution or function to help with this?