My Leopold also resonates on certain keys, but it ain't no thang. Even this glorious Ninja has a little bit of ziiing, but not nearly as loud as the Leo or other Ninja/MJ2's. Most of this thread (and that other 20+ page Ninja thread), while entertaining, doesn't particularly address where the sound is coming from: the metal plate. Correct me if I'm wrong, but I believe what we have here is a music box kind of situation whereby the sound of the spring in the switch is amplified by the metal plate.
One would think that decoupling the switch from the metal plate shouldn't be too difficult, or at least dampening the metal plate.
Now then, my Deck at home has a ringing 'N' key, obviously from typing 'Ninja' so often into Geekhack. Anyway I'll crack it open tonight and see if I can get the [strike]ring[/strike] zing dampened, thus proving that I will be the greatest keyboard dork on the planet!