Then I found the answer much closer to home..... It was coined by tsuwm on this very bulletin board - see "British v American" thread in Wordplay and Fun - on Wed 30 Aug 2000. And I quote:
>the structure of this board makes moving
from thread to thread a little awkward
Yet Another Rehashed Topic! (time to coin an acronym: YART)

As the inspiration behind tsuwm's coining the phrase (or, perhaps, the grit in his oyster responsible for that pearl), I feel that it is probably the most significant contribution I've made to this board!