Quarterrific

The 50 State Quarters program was the release of a series of commemorative coins by the United States Mint. Between 1999 and 2008, it featured each of the 50 individual U.S. states on unique designs for the reverse of the quarter and will feature the District of Columbia and five of the nation's territories in 2009.

The program was conceived in hopes of creating a new generation of coin collectors. Roughly half of the U.S. population collected the coins, either casually or as a serious pursuit. Thus far, the U.S. federal government has made a profit of $4.6 billion from collectors taking the coins out of circulation.

See all the designs at Wikipedia.