[Craig]

This is just what Tagoman looks like it can do.
I've attached a bit of a screenshot.
By clicking on the "tag://apha10" that I've typed into the comment field of the project, Tagoman opens the window that shows three things I've previously attached the "apha10" tag to: a folder, a scrivener file, and an email message.

EDIT: I should add that that little window can also be drag-and-dropped-into, so it works well to build a collection of related files as well as to retrieve them.