Here's another song that might get put in the list, although there's 2 people singing at the same time with different tones. Hope it gets in MLK:SiM. :)
There's no cover art but the author used this picture for his video so maybe you could use it as a cover art:
http://browse.deviantart.com/?q=Communist+Dash#/art/Communist-Dash-213342121?_sid=7e54a62a
Lyrics:
QuoteUnited Forever, In Friendship and Neighbor,
Our Great Equine Empire shall ever endure,
The Mighty Celestia in all of her grace,
Created this world to be our sacred place,
Long live our Equine Motherland,
Long live our Empire oh so Grand,
Long live Equestria united and Free,
Strong is our Friendship Trialed by Fire,
Long may that Violet flag Inspire,
Shining new glory for Ponies to see,
With Luna our princess, Our Ever Loved Goddess,
The Elements of Harmony Returned her to Grace,
The Night was Eternal, Her punishment Infernal,
Nightmare Moon was put into her Rightful Place,
Long live our Equine Motherland,
Long live our Empire oh so Grand,
Long live Equestria united and Free,
Strong in our Friendship Trialed by Fire
Long may that Violet flag Inspire,
Shining new glory for Ponies to see,
The struggle continues, The parasprites are bad news,
But we see right through them, we know they were abused,
With Faust our creator, we destroyed the invader,
And see Them become a Cutie Mark Crusader,
Long live our Equine Motherland,
Long live our Empire oh so Grand,
Long live Equestria united and Free,
Strong is our Friendship Trialed by Fire
Long may that Violet flag Inspire,
Shining new glory for Ponies to see
Long live Equestria our motherland! (http://imgur.com/vyD7jwT.png)