Apple refuses to classify the iPod as an mp3 player. They are right in doing so, but this has some consequences online : searches for mp3 player in google don't point to apple.

For several years Apple.com has enjoyed a first page ranking for the terms MP3 Player, MP3 Players, and often top 10-20 rankings for related terms like MP3 device, digital music player, and others. Today they no longer rank in the top 100 for keywords that they should dominate like MP3 players and simply MP3. (MarketPosition)

If you work with websites and keywords a lot, you can see why this is an interesting story.