Back when everyone was smoking cigarettes wherever the hell they wanted, concertgoers apparently did this thing where they'd wave their lighters around during certain songs? Or something like that? That was before my time so I don't really know - I had to turn to the anthropologists at Wikipedia to get the historical scoop:
Sometimes at rock concerts, lighters are held in the air to signal an encore or a power ballad. With the decline of smokers, the restrictions placed on carrying lighters during air travel, and the increase of cell phones in the early 21st century, cell phones are used in place of lighters. While this is generally frowned upon by older fans, it is still becoming increasingly popular.
Ah, so that's why people might want the official Zippo lighter app on their Android phones, complete with a realistic flame that reacts when you wave it around and customizable with dozens of different lighter designs. Got it. Now what the hell's a power ballad? [Market]