The blurry, transparent background in Notification Center, Control Center, Spotlight and other more options menus on iOS 7 device can make reading experience rather unpleasant.
If you don't have installed program for editing PDF documents on your computer, then you can use web application PDFescape which allows you to edit your documents in your browser.
Mac OS X Mountain Lion has 43 secret desktop wallpapers hidden in one of its folders. They are all beautiful, high quality and this is how you find them.