Here's a simple and clean one I made (using Photoshop Touch on iPad).
The apple is taken directly from an illustration of the iPhone 5 on Apple's website, and the colour is taken from the colour used to represent the black anodised aluminium back of the phone in the same illustration.
I like the simplicity and the fact that it's derived from Apple's graphics.
The slightly lighter solid colour works well as the home screen.
On my personal version I added my name and contact info faintly under the Apple.
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