Which sites have special discounted giftcard bonuses?

I'm not sure how to describe it perfectly, but to use Swagbucks as an example:

Once a month, you can cash out a $25 gift card for just $22 on Swagbucks (I think Paypal is the only one you can't do this for).

So, despite the minimum payout requirement for say, an Amazon Gift Card on Swagbucks being just $3, you wouldn't want to claim a $3 Amazon Gift Card until you'd claimed your $25 one for that month.

Do any other sites do something similar to this that it would help to be aware of before starting to claim prizes? I know most people want to cash out ASAP on new sites just to make sure it works, so having a heads-up about these sort of intricacies would be nice.