Have you tried Tagxedo? It’s a pretty nifty little app I spotted on @liendi11′s Amplog recently. While playing around with it I realized that it was more difficult to get the clouds to work in WordPress than one would think so when I found a way to get it to work I also created a video to explain it. The method that I demonstrate shows you how to create a tagxedo cloud that is usable in both pages, posts and even as a widget. The main thing that needs to be modified is the size of the iframe code that is provided in the tagxedo code snippet. Here is the video followed by a live example of the tag cloud.
In the live example of a Tagxedo Tag cloud below you’ll note that all of the links go to the default function in the setup – a Google search page. Ideally a blog specific search should be used. I’d imagine someone will get creative and port it to a WordPress plugin before too long but until now you can see the possibilities. (Note: If you click the tags it will take you off my site and to Google search, apologies I should have adapted it to my site search!)