my favorite product name is the ButtKicker, which replicates the shaking associated with very low frequency sounds. install one under your couch in the ht room and it, umm, kicks butt. saw this at ces2001:
http://www.thebuttkicker.com/buttkicker_shaker.htm
-kelly
http://www.thebuttkicker.com/buttkicker_shaker.htm
-kelly