Parents, the safest way to keep your kids from accidentally spending your money in any of the iTunes stores, including the App Stores, is to give them their own iTunes Account that doesn't have an associated credit card.
Whether you want to let your kids play around safely, or just don't have a credit card, you can use an Apple Account with no credit card to try one of the hundred free apps in the new Mac App Store or download free apps on an iPhone or iPod touch.
You can't create an account in the main iTunes Store without a credit card, but you can from the App Stores.
From iTunes, if you're already signed into an account, sign out. Choose your country (use the country