App Sketchbook is a pretty nifty notebook for iPhone developers who want to sketch out their products out on paper as part of the brainstorming process. App Sketchbook has three pre-drawn, full-sized iPhone templates per page with ruled lines beneath for notes. A pixel ruler runs alongside the template. You can use them in conjunction with iPhone UI stencils to get your ideas down on paper.
The App Sketchbook is a wire-bound notebook with 100 double-sided pages. It costs $
Edit (1:30 PST): Apparently make that $16.95USD as apparently the Web site updated right around the time I made my original post. A screencap of the original price is available here.