From www.wdwinfo.com

New designs to be featured on Disney Dollars
Dec 29, 2012

Beginning January 1, guests at Disney will be able to purchase Disney Dollars with new designs. These can be used as "cash" at the theme parks; some fans collect the dollars as artwork or souvenirs. The Disney Dollars will be available in a $1 denomination and can be purchased at Guest Relations offices in the theme parks and Downtown Disney, as well as at the Front Desk and Concierge desks at the hotels.

Due to the popularity of gift cards, Disney Dollars have not been as widely available as they previously once were. The Dollars bear the image of a Disney character or a drawing of a Disney landmark and were first issued in May 1987.