noise cancelling headphones

Not familiar with any aftermarket units which offer this for the driver, some offer systems in which it plays to rear headsets with a dvd soundtrack while the radio etc plays up front.

You can always install a switching box on the speaker outputs and run the speaker level output to a High to low level converter, which will give you a line level output for rca leads etc.. This is suitable to run headphones, so you could use any existing noise cancelling headphones off any head unit.

I noticed the other day that honda now have noise cancelling built into their standard head units in the high level cars, so its only a few years away for the "affordale" vehicles.

Hurketc,
there may possibly be what you're after on the market, but it would not be too difficult to cut into the existing speaker wires and install a stereo phone jack to run the headphones. Just make sure that the jack incorporates a switch to turn on/off the speakers. The earphones are a higher impedance but that wouldn't be a problem.
You can pay $250 for a pair, but I bought a pair of noise cancelling phones from Jaycar for $50 which work very well, tho you wouldn't want to have large ears, as the earpads are a bit small. What I really found them good for was killing aircraft noise on the plane, running them without any sound, just noise-cancelling. Really managed to sleep with them on.
Gerry

I would think that most of the noise cancelling headsets work from a standard headphone jack. The noise cancelling part is generated in the headphones themselves rather than the audio source. Just need the head unit to have an output for headphones.

If you want them for passengers then I have no drama at all but if it is for the driver then need I state the obvious that using headphones while driving would be pretty dumb idea (if not illegal). Besides having no idea how the vehicle is revving you would have absolutely no idea of the emergency vehicle coming at you with sirens blaring. One of my pet hates is people cocooning themselves in vehicles with loud music and being totally oblivious to what is going on around them.

Not directed personally at you but I have seen it too many times.

Muddy