An economics professor at Loyola Marymount University analyzed auctions of gift cards on eBay and found that gift cards from certain stores fetched consistently lower sale prices than others. Professor Jennifer Pate's research suggests gift cards are less valuable to recipients when given for stores that offer less product variety and fewer locations.

The study, which was published in the Journal of Economic Perspectives, also revealed that the average gift card is resold with a 15% discount. "In other words, people who receive gift cards are willing to accept around $85 in cash in exchange for a $100 gift card. For many gift givers, this means that a $100 cash gift will go much farther than a $100 gift card," said Pate.

Ranked according to their resale value, the ten "best" gift cards are Home Depot, Lowe's, Office Max, Circuit City, Starbucks, Old Navy, Wal-Mart, Target, Staples and Best Buy, all selling for above 86% of their original value (a 14% maximum discount). The five "worst" gift cards are Tiffany & Co, Victoria's Secret, Abercrombie & Fitch, American Eagle, with Express coming in last at 74% (a 26% discount).