Ultimate Battlefield 3 Simulator
If you are currently building up your PC and think it will be immersive, then take a look at this setup which will be showcased on The Gadget Show (overseas)
Of note is it looks like there are paintball guns trained on you to simulate taking bullets – ouch!
This was pointed out by Helios in the movies section of the forums
http://clanheat.com.au/forum/viewtopic.php?f=6&t=8656#p73802