If you're like most consumers, you've bought about two dozen songs from Apple's iTunes. Where do the hundreds or thousands of other songs on your machine come from? They're ripped from CDs you own, or those your friends have lent you, or from files you've "shared" on the Web. It doesn't matter. What matters is that the iPod improved the way you listened to music: It let you carry most or all of your music collection with you, without having to pay a penny to do it. And the Kindle can't do that for books.