I love getting gift cards. I fucking love them. Unless it's to someplace shitty, like the Hallmark store or something. I'd rather get a $15 gift certificate to Borders than have you spend $15 on some shitty wall decoration that I'll hate but have to display because it's manners.
Gift cards are awesome because you're giving people want they really want - a shopping spree. Sometimes food gift cards are a great idea, such as cards for Starbucks or Dunkin' Donuts, if you happen to know that the recipient likes those places. But here is where you cross the line between "Something you might find useful and fun to treat yourself with" to "I have completely given up":
That's kind of trashy, FYI. And even if you're giving it to someone who LOVES Burger King, you're doing more harm than good. "Yes, tubby, go eat a big juicy burger. Have some greasy fries, too, that's right. Ask for extra mayo on that burger, because it's a gift card and what better gift can I give you than a fucking coronary?"
Do both of you a favor and just give a Wal-Mart gift card. Same level of trashy, but you're not responsible when the recipient (after having spent the card on donuts and soda) has a myocardial infarction.