More than 67 million iPods have been sold since 2001. An additional 17 million are expected to be sold by year's end, creating a cottage industry for iPod accessory makers. For every US$3 spent on an iPod, $1 is spent on an accessory, said Steve Baker of the research firm NPD Group. The industry posted $850 million in sales in 2005 and is expected to eclipse $1 billion this year.

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