Dixie Chicks - Long Time Gone (Hank Williams, Johnny Cash)
Much too young to feel this damn old - Garth Brooks (Chris Ledoux)
Good Ride Cowboy - Garth Brooks (Chris Ledoux)
Look at me I'm Sandra Dee - From Grease (Elvis)
Cowboy Love - John Michael Montgomery (George Strait, George Jones)...
Can't be bothered to read all through this thread to see if it's been mentioned, but Simon Mayo and Mark Kermode discussed this in their podcast this week.