text: Edward C. Baig: Personal Tech - DemoMobile provide advance look at gadgets on the go (USATODAY.com) USATODAY.com - Sitting at the airport, you pull out a laptop or personal digital assistant and watch TV, delivered through Wi-Fi. Perhaps you'll grab an MP3 player instead, but rather than listen to downloaded tunes, you check out Internet radio. Or maybe you'll just make a call but thanks to the headset into which you are speaking, the person at the other end can make out your voice and not the blur of jet engines taking off at the same time.