When placed in a folder, the Tag Search object (TS) would compile and display a list of all the tags used on objects within the folder and its sub-folders. It's Properties would let you limit the depth of sub-folders to be searched. Display options would let you set how many tags should be displayed, and how to order them (alphabetically, by popularity, or most recent). Tags would display the number of matching items in parentheses after the tag.

Each tag would be a link which would list all the matching objects. It could either go to the TS object and list them there, or it could work as an Ajax widget that would list matches wherever the object had been placed in an appearance, replacing the tag list with the matching objects.

When listing matches within the TS object, the list of tags could be in a right-hand column. Clicking a tag would filter the list of matches, and it would also filter the list of tags so that you only see the tags that are also used on the objects that match the first tag. You can then click a second tag to hone your choices down even more.

As an Ajax widget, the tag list would collapse to show just the chosen tag, letting you clear it by clicking it again. A + sign next to the tag would give a pop-up of all the tags, letting you add a filter to narrow your choices.