The term "hovercraft" in this case refers to a vehicle that hovers above the ground at a constant distance (usually under a few feet), so as to have no resistance with the ground. Because of this, the "hovercraft" would theoretically be able to reach much higher speeds than current vehicles. This is commonly called an "anti-gravity" effect, but I try to avoid using this word, as the effect described is not really anti-gravity. If something was truly anti-gravity, it would either shoot away from the earth into space, being repelled by the gravity, or be completely unaffected by gravity -- floating around the air. This is not the idea here; the hovercraft is a vehicle that stays at a height relative to the ground beneath it. Below are my thoughts on it.

When I think of how such a vehicle would work, I picture a sort of thruster at the bottom pushing down that is regulated by a computer. The thruster would have to be rapidly turned off and on (or finely regulated) to keep the vehicle at a constant height, or else it would just fly straight upwards. As for the thruster, I'm not sure what one could use. I picture something that takes in air, ionizes it, then forces it downwards through electromagnets powered by an AC power supply -- it attracts the ions until they reach it, then switches polarity so as to repel them (the ions) downwards. As for the computer, we already have the technology to be able to regulate something like this. Laser beams could be used to see how far away the vehicle is from the ground, then relay that to the computer that controls the thruster. It would then turn it (the thruster) on when it's below a certain height and turn it off when it is above a certain height. This would probably even produce the "wave" motion that is sometimes seen in movies.

Let me know if you have any ideas for the thruster or if you want to modify/shoot down mine.