Has Anyone Used Any Of The Online Gift Card Exchanges?

Jordan Catalano
Broadway Legend
My Mother got a giftcard worth quite a bit for a store she doesn't use often and I was telling her I remembered these online exchanges. I went to use the google machine to look them up and there's quite a few of them so I was curious if anyone here has used them to trade/sell/buy and what you thought.
"I think Glee is way too sharp, smart, witty, clever and emotionally confronting for the masses." - Dave19 - "What's next? Snow Black and the 7 Swaggers? Shasquirta and the Beast? 101 Weavematians? Willis in Ghettoland?" - Dave19, in reference to the new ANNIE remake.