Dragon Quest IV: Michibikareshi Monotachi

In chapter 5, enter the tunnel between Branca and Endor. Go through the tunnel and up the stairs on the other side. Re-enter the tunnel, and go up the stairs on the other side. Keep doing this and eventually you'll get 2000 free coins to use in the casino! But you can only do this trick once, I think.

This weird glitch only works in the Japanese version of the game. When you're fighting any boss, choose to escape 8 times. Each time will fail, but if you do this procedure, for the remainder of the battle your physical attacks will always be critical hits! It doesn't matter what you do in between the failed escape attempts; you ARE allowed to do other things (such as cast spells) in between each escape attempt, but be sure you can survive getting attacked freely for each escape attempt.

In Chapter V, after you have found all seven chosen ones (Ragnar, Alena, Brey, Cristo, Taloon, Nara, and Mara), you can change the music on the overworld. Place Ragnar at the lead of the party if you want Chapter I music, place Alena, Brey, or Cristo for Chapter II music, Taloon for Chapter III, Nara or Mara for Chapter IV, and the Hero for all-new music. If you want the Hero's old music, set him/her at the head of the party with no one else in it.