Dan McLean Jr's "Tactile Sound Transducers"

OK, here's the basics. TST's are basically sub-woofers which you sit or stand on: The sound vibrates into your body.

Tactile (perceived by touch)
Sound (duh)
Transducer (any device for converting a signal from one medium of transmission into another)

A typical example of a normal sound transducer is a speaker. It converts an electrical signal into vibration. That vibration of air enters your ears, and travels down your ear canals to your ear drums.
In reality, that first example is an over-simplification. The higher the frequency, the more it follows that example. The lower the frequency, however, the more it follows this second example: The vibration of the air is collected by your entire body, and vibrates up to your ear drum. This process is called "induction".
Higher frequencies enter through your ears, but lower frequencies enter through your body by induction.

Essentially, TST's ay're more efficient than normal speakers because they bypass two entire transdution processes;
Transduction from the speaker to the air, and
Transduction from the air to your body

The TST is like a speaker, in that it vibrates, but if you attatch it to the bottom of your chair, it's induction through your body is much more efficient, and you hear deep, thundeing bass! What's just as cool is that people who are not in an efficient path of induction hardly hear a thing, even if they're only a foot away! As you'll remember from the two early examples, this is only effective for lower frequencies, since the higher frequencies actually need to be gathered by your ears. That means you still need normal speakers, or headphones, as well.
How can this be applied in the real world? Well, if you install a TST under your seat on the chesterfield (couch) and wear headphones, your home theatre can rumble you from here to Mars, and the person in the next room won't hear a peep! You can have rockin' bass in your car, without pissing off pedestrians, and without filling yor trunk with electronics. Computer games, arcade games, amusement park rides and movie theatres all use this technology, and it's use will be much more widespread very soon.
I work in the technical side of the music industry, and our application of TST's (sometimes refered to as "shakers" or "butt buzzers") is for musicians in live performance. I'll spare you the industry-specific technicalities here. Let's consider it sufficient to say that TST's, when used in conjuction with In-Ear Monitors, can preserve an artist's hearing for years, and dramatically improve the quality of the sound heard by the audience.