On many sites, tags are a secondary way of navigating the site. Sometimes augmenting categories, on other sites they act as the primary navigation. Recently, I’ve read backlashes on the use of tag clouds as a navigation tool. The argument is that if you get too many tags in a cloud, it’s a mess and hard to read, and in some ways a tag cloud means you can be lazy and not categorize things cleanly.
One new classified ads site called theadcloud.com is testing how well tag clouds work for navigation and organizing content by making tag clouds the navigation tool for looking at local classified ads.
In my tests in browsing the site I found the clouds fairly easy to use, but I think as the site grows and more cities are added and more tags per cities, it could get cumbersome. However, I think we’re still early to make a judgement on the best uses for tag clouds. We’ll get there.