As soon as your wife has given birth do NOT name the baby but go outside and into the village talk to someone who should be at your house and then go back you wife will have given birth again but the baby will be the opposite gender from last time and note that you only get one baby from this.
After you start a new game and have gone through the very long introduction of meeting everybody and have gone to sleep, head out of your farm the next morning. Once you name your dog don't head for the tool shed. Instead just grab the weeds and toss them and grab the small rocks and throw them in the water. Doing so makes time freeze at 6 AM. If you were to head into a building or to use a tool the time will start moving.
If your dog is standing to the right of the table when your house is expanded, it will get stuck in the table when the expansion is complete.
These unlockables are unlocked when playing through the game and performing certain tasks.
Hold R + L + Select immediately after the lights go out when done writing in the diary. You must hold down the buttons the entire time. Eventually you will see the ending sequence that would be given to you if the game ended at your current level of progress.
At some point in the game, you can randomly find a rabbit on the mountain. If you run up to it and press A, you catch it. Then the hunter runs up and offers you 1000G to let it go.