You guys read my mind. I have been using Dolby Headphone technology with PowerDVD and really rocks.
Encoding the tracks previously is not an option if you play your tunes also through speakers. Something like a "sound enhancement" option will be perfect. Dolby Headphone options in iTunes would make the perfect pair.
Also believe an iGadget (iPod + Phone + Organizer + Camera) is not on the market for commercial reasons, There is no technical limitations.