Pantech Vega LTE allows for gesture navigation to avoid finger grease
They use the front-facing camera to read your hand movements, and the phone reacts accordingly. For now it supports the most common situations, like waving to answer a call, flip an e-book page, browse pictures in the Gallery, or change a song, after your hands have been buried deep in the KFC bucket (or while making dough, as in the promo video below).
Qualcomm has been experimenting with gesture recognition after acquiring GestureTek. So has Texas Instruments, which is powering the new Samsung Galaxy Nexus and Droid RAZR, so hopefully we will see similar tech in other Android handsets soon.