Subway cool set has been made of 6 metrocards featuring interesting facts and images about NYC subway system. All cards were initially sold separately. In the end MTA issued collectors set in plastic folder with all 6 cards in it and each card encoded with $6 to ride 4 times (at the time price of a ride was $1.5). Here are images of that set: 1, 2, and 3.

All cards had circulation of 50,000. Number of sets issued for collectors is unknown. Each card has many images on it and each displayed stats in the center of the card.

Set has been sponsored by citysearch.com which at the time was selling metrocards on its website.