Last night on The Tonight Show starring Jimmy Fallon, Billy Joel joined the talk show host in a doo-wop video so entertaining that it was singled out by Tim Cook on Twitter. Check this out. @jimmyfallon and @billyjoel with iPad and a cool app called Loopy HD. Magical. http://t.co/dWlZr6Lsm6— Tim Cook (@tim_cook) March 21, 2014 The featured iPad app is Loopy HD [Direct Link], which allows you to create music by layering loops that you record y
