[Tulsa]

For those who do not prefer to have the difference in font sizes, it's controlled in the template: Tag Templates > tag_cloud_headinclude

<style type="text/css">
a.tagcloudlink:link, a.tagcloudlink:visited { text-decoration:none; }
a.tagcloudlink:hover, a.tagcloudlink:active { text-decoration:underline; }
a.level1 { font-size: xx-small; }
a.level2 { font-size: small; }
a.level3 { font-size: medium; }
a.level4 { font-size: large; }
a.level5 { font-size: xx-large; }
</style>

Just change the font size, "xx-small", "small", "medium", "large", "xx-large" to whatever size you would like.

The levels and how many you use are controlled in vBulletin Options > Tagging Options > Tag Cloud: Number of Levels