From 9to5Toys.com:

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Today only, Best Buy takes 20% off $100 iTunes gift Cards, both physical and digital delivery. Note that international US iTunes users are eligible to purchase digital because the gift cards will be emailed for redemption but must use a US credit card or Paypal.

iTunes gift cards are good for Mac Apps, iOS Apps, iTunes Music, Videos, iBooks and more.  You are basically getting 20% off any media you’d buy at Apple.

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