I thought this Chalk-it-to-me Piggy Bank was pretty cute. It is made from a pigmented ceramic that you can use as a chalkboard. That way, you can draw on the piggy or write a reminder of what you’re saving for. $60 from Ladies and Gentleman. (Via The Sub-studio Design Blog)
ETA: If $60 seems a lot for this particular bank, you can always get a piggybank from the thrift store and spray it with chalkboard paint.