One of the cheap thrills most of the mothers I know have is exchanging postcards. They write personal notes or messages on store-bought or personalized postcards and send these postcards to people either in the country or abroad. I bet they enjoy mailing these postcards and enjoy it even more to shop around for postcards to give out to their fellow enthusiasts. They probably spend one hour too many in bookstores or specialty shops in search for the most beautiful or rarest postcards to send. I bet they would even be too preoccupied with their mental postcard shopping list to even notice the receipt printer sitting quietly by the till.