The cool cat at //engtech has created a nifty work-around for edublogses and other WPMU sites to generate a “tag cloud” of most used categories in your blog.

Tag Cloud Generator for Wordpress.com
http://engtech.wordpress.com/tools/wordpress/tag_cloud_generator_for_wordpress/

Here are the results for this uniblogs site.

(2)   (38)   (8)   (5)   (9)   (12)   (1)   (145)   (11)   (9)   (13)   (29)   (6)   (40)   (13)   (14)   (3)   (40)   (12)   (8)   (1)   (6)   (23)   (8)   (24)   (17)   (9)   (2)   (20)  

Created by Wordpress.com Tag Cloud Generator by //engtech