Off the top of my head, ArmA with TrackIR already implements a control scheme like this.
Operation Flashpoint already featured a control scheme that allowed the player to detach look control from gun-pointing and walking-direction control, and that carried over to ArmA. Of course, without an additional input device, it's somewhat useless, as you have to give up control of your gun to gain control of your character's head. So that's where a bunch of markers attached to the player's head come in. Even without that, it's still useful to be able to quickly glance around while in full sprint - something possible in real life, but impossible in most FPSes, where your camera/character's head is fixed rigidly to his body at all times.
I recommend that at install time, the user is presented with a window containing randomly ordered buttons for 6 of the top web search engines on the market today. By selecting one of the buttons, the user makes that search engine the default. This should keep everything fair and everyone happy.
(now we just need to find 6 search engines that people actually use)
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