Did anyone mention "Streets of Laredo"? I can't hear that song without thinking of the movie "Bang the Drum Slowly," the best baseball movie ever--with a truly amazing performance by Robert De Niro as a catcher who is dying of cancer--after the team learns the catcher is sick, he leads them in singing the song.
Another one I didn't see above is "I Ride an Old Paint." And how about "Git Along, Little Dogies"? --seed