More than 50,000 movies are being rented and purchased each day from iTunes.
The major competitors of iTunes is Wal-Mart and Amazon. Amazon is different in the sense that it sells music that is free of digital rights management technology, so buyers can play the music in any media player.
So while digital rights management free music sounds like a stellar deal, Amazon's music store isn't a threat to iTunes.
Maybe as the word spreads, it will become more popular.