I have a table which contains all the distinct tags which have been used within the document, along with a count of how often they've been used. Clicking on the tag-name shows all the places it is used - via org-tags-view.

I guess I call it a tag-cloud, even if it isn't formatted like one would imagine on a web-page.

No package, just a bit of lisp-magic. I'd be happy to share an example if it were useful.