For quite a while Amazon has been offering a free app every day, to encourage use of their app store. Sadly the store is only accessible for Android users, but Apple has finally adopted a similar promotion.
Starting this week, iOS users can snag Cut the Rope Experiments for free. This includes both versions (iPhone / iPad) and will be free for the remainder of the week. You can find this app and all future apps via the Free App of the Week banner in the iOS store. Sadly only time will tell what apps will appear there, but considering the new iPads focus on gaming elements, we should see many more games.