More courses:
Hold X + Y at the options screen. Select the "Password" option that will appear. Enter one of the following case-sensitive passwords to unlock an additional course:

Enter CinqueValvole to unlock the Fiorano course.
Enter LiebeFrauMilch to unlock the Nurburgring course.
Enter Stars&Stripes to unlock the Laguna-Seca course.
Enter KualaLumpur to unlock the Sepang course.
Enter DaysofThunder to unlock the Atlanta course.

Full pause screen:
Press Start to pause game play, then hold X + Y.