There's an AmazonLocal offer for $4 off any MP3 album $7.99 and up. Unfortunately, this $2 credit (MP3S4ALL) can't be used for it, but the $1 credit I mentioned should work. Only US customers eligible and one voucher per customer. You have until midnight tonight (Pacific time) to claim the free $4 voucher and until 20 Jun to use it. You won't be charged for it, nor will you be obligated to use it.
Other music news has the Amazon Cloud Player now available for iOS. I like it much better than iTunes. I'm using it as I type - listening to Fantasia on my iPt4.