A tag cloud is a visual depiction of user-generated tags, or simply the word content of a site, typically used to describe the content of web sites. If you want to create one, you can get help from this link. http://www.petefreitag.com/item/396.cfm
I use tag clouds on a few of my sites. But I wanted to be able to control which links are the largest so as to be able to "steer" people to the pages I want. So it's a tag cloud that monitors which pages are most popular, AND you can tweak the results to pages you want also: Tag Clouds for HTML Sites