http://www.thebuttkicker.com/gamer2
Overview
The ButtKicker Gamer2 lets you feel all of the action from your games and simulators.
Feel the gut-wrenching punch of machine-gun fire, the pounding of chopper blades, explosions, racing engines, gear shifts, rumble strips, landing gear, engine throttle and more.
Turn down or turn off your subwoofer and still feel all the bass - even while using headphones.
Take your game or sim to the next level of realism.
Ok, a co-worker brought his ButtKicker today to work and I've had the pleasure of trying it out. This is so damn COOL!
Besides the insane vibration with certain musics that made me an instant fan of it, I tried it it out with gameplay videos and it's awesome: Every time a ship fired it's cannons the chair vibrated, when there was an explosion, vibrations. Honestly, this + Oculus Rift must be an insane experience.
What might turn off some people is how loud the vibrations can get, you need good headphones to isolate yourself from the noise.
EDIT: Ok, I had to try it again using a gameplay video of Space Marine with my favourite weapon, the Heavy Bolter.
I LOOKED LIKE A KID IN A CANDY STORE! Every time it fired, the vibrations... Even the Space Marine walking made it vibrate, but when it started shooting. It's bliss. Pure gaming bliss.