I simply had to register on this forum just to reply to such a topic.
http://www.youtube.com/watch?v=vMnLoOnrwbg
In my opinion this perfectly suits the game; in fact, I am almost stunned it wasn't included in Fallout 3. It suits New Vegas even more, because it references the 'West'.
And it suits the series simply because it features a man singing about he needs wide, open spaces to roam around (i.e the Fallout games and free roaming games in general).
Oh, and there is Bing Crosby's incrediable talent.