I just thought of a possible combo: Plaza & Counting House. You use your Plazas to discard all your Copper, and then on the last action (or if you're out of other cards, like Plaza, to play) of your turn, you play a Counting House and draw all the Coppers back.
I've never played with this strategy before, but it was just something I noticed that seemed kind of interesting. This type of strategy would be even more interesting with a source of +Buy, because all of those Coppers and extra coin tokens could be used and none of them wasted.