Product review (5 stars): They work!
I tried the Home Depot rubber pads and got some improvement, but the noise was still too loud.  Silent Feet has cured my vibration problem.  The drier was always OK, but the washer sounded like a jet taking off and the vibration was terrible.  The washer is still a little noisy (Silent Feet doesn't fix that problem), but the terrible vibration has been greatly minimized.  Pricey, but I recommend the product.