Spotify Premium Subscription
A Spotify Premium subscription is such a good gift for any music-lover. For Father's Day, you could offer to pay for your dad's first few months of the service, and he'll probably love it so much that he'll pay for it on his own after that. It's like an endless iTunes library on your own; you listen to millions of ad-free songs, create your own playlists, and download music so you can listen even without Internet. You can get Spotify Premium for just $1 a month for your first three months, and then it's $10 a month after that.