I think I remember hearing that the concept of the belly-button jewel originated with the harem-fantasy costumes of Hollywood because in more restrictive times it was considered indecent for the belly button to be showing
I've had one for a couple of years and love it. I've never had any problem with infection or anything. It also didn't really hurt. My second piercing in my ears hurt worse!
Related question: How long did it take to heal?
I was picturing Tara Reid.