On several occasions apps that provide functionality unwanted by Apple have appeared on the App Store. Shortly after their true functionality is publicised they are removed as part of the approval process.
On 11th March 2013, HiddenApps was approved and appeared in the App Store. This App provided access to developer diagnostic menus, allowed for stock Apps to be hidden and enabled a opt-out feature for iAds, Apple's developer driven advertisement system.
Read more about this topic: App Store (i OS)