Found an interesting article over at a fairly new site, Windows SharePoint Services (WSS) V3 Search (WSSSearch.com). It has a free solution that allows you to add tag clouds to WSS.
This blog (Community Server) uses a tag cloud. It's the big glob of text that shows how popular different tags are. Each "tag" is given a weight, based on some value. For this blog, it's the number of posts I tag with that subject so looking at the blog you can see I post mostly about "SharePoint" and the least number of posts are tagged "Website". It's very common these days and helps you hone in on the most popular stuff (whether it's blog entries, news items, whatever).
The guys on WSSSearch.com have put together a nice little package for 2007. It's a tag cloud and a web part so you can get a tag cloud setup on your site. My only wish is that they package it up as a solution file so you can just deploy it, rather than doing everything manually. In any case, check it out and see how you might use it. Hook it up to your WSS blog? Tie it into a document library? Or attach it to a Links list so people can see the most popular links.