The iPod is essentially a portable hard drive with headphones. Apple CEO Steve Jobs and his team of savvy engineers revolutionized the entire music industry with the iPod. A 30-gigabyte iPod that holds 7,500 songs and 40 hours of video costs $249. The price goes up from there, depending on added features, or skip the video and the price goes down. Still, on average, that's about $18 million a day and more than $6.4 billion a year -- music to Apple's ears.