Gradient wallpapers are always a great way to give your device a very neat minimalistic look. They're not distracting and can make icons on the homescreen a lot nicer looking.
Blur is an awesome iPhone app that lets you create your own gradient style wallpapers from any picture you like. You simply browse for any picture in your library, then use a slider to change the effectiveness of the blur.
It's an awesome way to make a wallpaper from nearly any photo you've taken yourself.