Here is an even more obscure privacy setting. If you read through the privacy page here...
You'll notice about halfway down the page in the "cookies and other technology" section a discussion of interest based advertising, which is basically iAd's targeted at you based on your usage habits. The only way to opt out of this "feature" on an iOS device is to click on the link in that paragraph to http://oo.apple.com/
from Safari on your iOS device, which will bring you to a settings page that will allow you to disable "interest based iAds". I have not found a way to get to this setting page through the settings App (queue up the people who will promptly correct me).