Time Travelling

Animal Crossing Wild World
when you get to the select character screen select the phone up at the top of the bottom screen, then say reset clock and change the date to whatever you want.

Animal Crossing City Folk
It's best to change the time on the wii instead of the time on the game because It will effect plants and bank interest when you change the games clock. At the wii menu click the wii button on the lower left side of the screen an select setup then go to calender and change the date or the time.

Good

 * you can get to your favourite festivals quicker
 * if you miss a festival or event you can go back to it
 * you can get mail quicker
 * you can get bank interest quicker
 * new people move in faster
 * fruit will grow back on trees

Bad

 * Villagers will move away
 * weeds will grow
 * the villagers will not know who you are
 * flowers will die
 * you will miss out on some days of Nooks items
 * You will miss out on some of the Mable sisters clothes
 * your mail box will fill up and you can't receive more mail