Wouldn't it be great if we could fill in a box saying what our National Anthem is called? You know, like "God Save The Reigning Monarch" or "Go Hang Yourself", or even a real song like "Word Up" by Korn.
It would be just like the Motto entry, only it would be the name of a song.
Just to add to the fun.
A number of suggestions have been made and rejected about adding new customized fields. The problem is that adding such fields (national anthem, capital, leader's name, etc) adds significantly to the overhead of the game, as well as other issues that have to remain unspoken.
You do have the option to go into great detail on your anthem via third-party resources. Check NSwiki's National Anthem (http://ns.goobergunch.net/wiki/index.php/National_anthem) page, and have a look at some of the creative solutions our players have come up with. There are multiple tools in NSwiki for customizing your nation's identity to your heart's content, and you can do it today. Check it out.