This holiday season, millions of Americans will contemplate what present to purchase for a relative or friend and then, out of ideas, they will buy a gift card. And each year, millions of people will forget to redeem them or spend only a fraction of their gift card’s value.

The amount of money that goes unspent each year from unused gift cards is staggering: $10-billion of the $100-billion spent on cards annually, according to some estimates. Now Plastic Jungle, a Web site that helps people sell or trade in gift cards, is hoping to channel some of that money to charities.

The company has started a fund-raising program that allows nonprofit groups to collect unused gift cards from any company, as long as each card is worth $10 or more, and convert them into cash.

The charities turn the cards over to Plastic Jungle, which gives the charities 70 percent of the total gift-card value.