One noticeable aspect of Apple's iPod advertising were the sheer number of iPod ads on television and in billboards. At the time, it seemed as if Apple was just being particularly aggressive with their adverting, but Steve Jobs' Biography revealed that those ubiquitous iPod ads were actually being subsidized by the Mac.
"I had this crazy idea that we could sell just as many Macs by advertising the iPod. In addition, the iPod would position Apple as evoking innovation and youth. So I moved $75 million of advertising money to the iPod, even though the category didn't justify one hundreth of that. That meant that we completely dominated the market for music players. We outspent everybody by a factor of about a hundred."
So, the so-called iPod "halo" effect resulting in more Mac sales was something that Jobs relied upon. In fact, it allowed them to outspend all their competitors for a large factor which further cemented the iPod's lead in the MP3 market.