Searched and no results for 'tagroll'. I thought it would be interesting to show a roll of tags in the sidebar which would update from both of the common tag origins:
1) .../tag/ rel="tag"
2) category names
creating a Tagroll list - length adjustable - which would place the newest tag/category terms used in the latest post (stripping duplicates, or filtering through a preset list) and place them at the top of the roll, and also pulling the terms out of their previous position in the Tagroll if they had been present.
A default option would be to search the most recent posts containing the selected tag/category term in the host WordPress. It might also be set up to point to other sources.
Anything like this in plugins that would adapt or already exists?