Paired with the Oculus Rift. And oh boy, get ready.
http://www.virtuix.com/What it Does:This little tool allows you to literally "step" into your game. The low friction surface and special shoes makes it so the game registers your movement, and it works perfectly. You don't slip because the ring also acts like a belt, keeping you in place without you feeling it.
Here are some demonstration videos.
http://www.virtuix.com/Imagine an early jog in Skyrim.
Running 500M in Arma 3. Holy stuff. You'd lose a lot of calories.
Its been funded and now you can re-order your own for about $499. Or buy one for your friend in this...$1000 duel deal pack.
Some pictures.

The receptors along the line allow you to do a number of moves, such as sit, crouch, jump and more.

The Omni itself, can be adjusted and sized to your liking.
Honestly, I can't wait for this. From what I've seen it does not look like a big let down.