I don't know about you, but I've heard a lot of sound systems while driving on the road.  I do like good, deep, clean, hard hitting bass - but nothing drives me crazier than when I hear that obnoxious "trunk rattle," when there's so much bass from that awesome system it feels like it's going to actually blow the trunk lid off of that poor Buick next to you on the highway.

What solutions are out there to  eliminate or suppress trunk rattle?  What kind of luck have you had with them?