What's a gas card? (or grocery card)

Recently a friend asked me what a gas card is.  Not an unreasonable question, since it's something we often ask our members for.  Gas cards and grocery cards are essentially gift cards with a certain amount of money on them that can be used in various places.  

We generally provide cards in $25 increments when we respond to requests for gas/grocery help. (See how we decide.)

Dillons and Hy-Vee make them available online, at the customer service desk, and at the checkout counter.  

The ones you get at Dillons are also valid at:  KwikShop, Kroger, Food 4 Less, and a host of other stores in other states.  They state they cannot be used for lottery tickets or money orders and cannot be exchanged for cash, except where required by law.

Hy-Vee cards are valid at Hy-Vee stores and gas stations.

Target cards aren't good for gas, but can be used to buy anything in the Target store.  Ditto for Wal-mart.

Anybody know of others?

UPDATE:  It appears to me that you can buy Visa, MasterCard, and American Express cards at Target and Wal-mart (and maybe elsewhere) online or in the store.  The difference is that if you buy a $25 Wal-mart card usable at Wal-mart, it costs  you $25, and your recipient gets $25 in merchandise.  If you buy a Visa card at Wal-mart (for example), it costs you $27.88, and your recipient gets $25 in merchandise.