I guess I'm fortunate. I haven't had a single vibration problem with my sub, other than when I was putting it through its paces with test tones and excessive volume. I got some shelves across the room the vibrate during those tests.
What I
have had real problems with is my washing machine during the spin cycle. The fron panel used to go wubba-wubba-wubba like someone was trying to using it as a thunder prop on a foley stage. I fixed it by slapping a large piece of Dynamat (left over from a failed computer-silencing attempt) onto the back of the panel. Now I have a very quiet spin cycle.
