drill down... a block to show which categories are most used, then narrow search results

My idea is to have it like del.icio.us pages. The taxonomy page will show you the most recent nodes tagged with that category, and an optional block will have

For example, folktunes.org/artists/clarence_ashley recordings have common tags like banjo, 78rpm, and singing, etc. Links in a block to the right would show the common categories, most used first, and have the option to add them to the search, thus narrowing the search. This could be done until the specific recording/story/whatever is found.

Hopefully this can happen in the 4.7 version.