UPDATE 4/28/16 : eBay is no longer allowing you to buy their gift cards using gift cards.
Today eBay has a deal to get a $100 gift card for $95. That doesn't seem to spectacular as its only 5% off. But... you can use gift cards to buy this. AND... you can do it again next time they have a deal... and again... and again.. By doing this you can make $5 in eBay gift card balance every time they have such a sale. So far as I've done it 4 times on Dec. 23rd, 27th, 29th and now January 8th. My original $95 is now worth $115. As long as they keep doing it there is no reason I can't keep getting $5 free every time.
I found the deals posted on Fatwallet. Todays deal is posted there. If you watch Fatwallet you'll see the $100 for $95 deals posted. It only then takes a minute or two to go buy a card.
Of course you do have to start with $95 and you've got to have a reason to want credit at eBay. They do have a variety of gift cards from other merchants (Target, Home Depot, Sears, etc) to buy so that could be a good use for you if you don't want to buy merchandise at eBay.
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