Perhaps it could display on the userinfo page: "X memories have been created from this user's posts." X would be hyperlinked to a page that showed which entries, who memoried (memorized?) them, and how many times (in the case of multiple memories for a single entry).
It could also be displayed on the LJ page for any entry, perhaps just as a hyperlinked number under the heart icon.
Just thought I'd throw that out. It could be useful.