Design Commission, a Seattle-based design house, has created a decidedly analog tool for iPhone app design: the iPhone Stencil Kit.
The Stencil Kit is made from stainless steel and ships with a Zebra mechanical pencil. The Design Commission site hosts free, printable PDF templates in letter and A4 sizes, both for use with the stencil.
The stencil lets you to trace the appropriately sized interface for iPhone app development, then add various controls such as sliders, icons, buttons, media playback controls, search tools, and dialogs. Using the stencil and one of the downloaded templates, a developer can easily sketch a quick rendition of what he or she wants an iPhone app interface to look like.
The iPhone Stencil Kit costs $16.95 plus shipping; you can buy it directly from Design Commission. We recommend this tool to any developer who feels more creative with pencil and paper when designing an interface.