Allowance accounts are a lot like iTunes gift certificates. You, the parent (or other financial authority), decide how many dollars' worth of Store goods you want to give to a family member or friend(from $10 to $200). Unlike gift certificates, however, allowance accounts automatically replenish themselves on the first day of each month—an excellent way to keep music-loving kids out of your wallet while teaching them to budget their money.
Both you and the recipient need to have Apple IDs. To set up an allowance, from the iTunes Store's main page, click the Buy iTunes Gifts link, scroll down to the Allowances section and click "Set up an allowance now". Fill out the form. After you select the amount you want to deposit each month, fill in your recipient's Apple ID and password.
Once the giftee logs into the designated Apple Account, she can begin spending—no credit card required. Once the allowance amount has been spent, that's it for music until the following month. (Of course, if the recipient has a credit card on file, she can always put the difference on the card.) If you need to cancel an allowance account, click the Account link on the Store's main page to take care of the matter.