Every day, the roughly one million people who visit the iTunes Store home page are presented with several dozen albums, TV shows and movie downloads to consider buying. This prime promotion is analogous to a CD being displayed at the checkout stands of all 940 Best Buy stores or featured on the front page of Target's ad circular. How do bands get these boosts? Who decides whether Arcade Fire is plugged at the top of the iTunes site - or whether Nickelback gets no mention?