I should be more specific… I have gone through the Theme Options and do not see an option to change the size of the tagcloud font. I also played with an assortment of font sizes in the Font page of the Theme Options to no avail. I also did a search in the stylesheet for “tag” but was not able to discern any that would have changed the size of the tagcloud. I don’t mind adding custom code, but I’m not sure what I would add if someone could assist me.
Changing the font size of the tag cloud is a bit involved since the functionality is native to wordpress. Pls have a look at the post for details on how to achieve it – http://wordpress.org/support/topic/tag-cloud-font-size.
Hope this helps.