NineParts is a development tool for iOS, OS X and Web. It allows you to preview proposed edge insets for a given resizable image and export sliced images for use on the web and with Cocoas NSDrawNinePartImage().
5 Stars - "NineParts takes the guessing game out of working with resizable images! Its a genius app. " - James P.
Developers: Takes some of the trial and error out of working with resizable images and gets you out of Photoshop!
Designers: Makes it easy to provide specific edge inset values for iOS development and sliced images for OS X and Web.