SharePoint Tagging Feature : kwizcom.com
I've been spammed by a friend recently with lots of interesting SharePoint related links. This one is a real gem. Have not tried it out yet, but the screen shots are very promising. A full tagging feature with tag management, tag clouds, search filtering with tag categories and tag cloud and more.
I was asked at my Search presentation about Tag Clouds for SharePoint and I wish I had stumbled upon this one before.
Check it out or your selves and tell me what you think!