Go to your Town Hall and go over to Pelly. Be sure to check that you're on the mat with a little picture of a house on it. Tell her you want to help out your town by depositing money in the town's fund. To get an exclusive Shopping Card to use for shopping sprees at the city, just deposit 10,000 bells into your town's fund. For other exclusive funds, deposit as much money as possible into your town's fund. The next day, you might just find a little surprise in your mail box from your Town Hall buddies!