Are you getting tired of other good icons? Hawk Wings, obsessed with all things Mail.app, has tracked down a Photoshop template for creating your own Mail.app icon. Courtesy of John Godfrey, this Photoshop template contains instructions for inserting your own images into a Mail.app icon, and Tim Gaden also recommends rotating your inserted image to 11.2 degrees counter-clockwise, as well as using an 85 x 90 size to get just the right fit.
But, "how do I turn an image into a Mail.app icon?" you ask. Hawk Wings has a solution for that step too: img2icns is a Universal Binary freeware app that can convert JPEGs, PNGs, TIFs and GIFs to the ICNS format, ripe for using a previous (and simple) TUAW Tip for replacing Mail.app's icon with your much more exciting new creation.