Apple enabled the use of iTunes Gift Cards for App Store purchases back in May of last year. So if you are funding your account balance with gift cards, Future Shop currently has $50 iTunes Cards selling for $40. You can also apply these cards toward the Mac App Store as well. That $10 in savings can result in free apps or software.
Future Shop had the exact same offer on June 11th, so these deals appear periodically. This current sale is good until August 25th.
Thanks to @OlivierCote for the heads up!