Tagadelic is a small module, without any databases, or configuration,
that generates a page with weighted tags. The cool thing is that
by merely altering font sizes, these lists suddenly gain a dimension.
Tagadelic offers various ways to add terms and vocabularies in one
tag cloud. By using the urls, you can create your own clouds pages.
It also offers a sideblock for each taxonomy tree.

WWW: http://drupal.org/project/tagadelic