Do you hate having to open up Photoshop just to design an icon? Gluestick is a small graphics editor that web designers will find extremely useful to prepare interface and icon designs.
The application lets you add two types of layers, text and image, and features a complete template set of Apple icons to work with ranging from accounts to alerts or folders. Open up the inspector window to set options like position, size, color, shadow and zoom. Your layers can be resized and Gluestick lets you really zoom in onto your picture so you can edit the details.
Although Gluestick offers many editing tools, I wouldn't consider it a proper graphics editor like Pixelmator though. The inclusion of icon templates and the fact that images are handled via layers makes it really ideal for designing interfaces and icons for Mac. The fact that it renders in CoreAnimation also ensure that your images look even crisper on a Mac desktop.
Gluestick will come in handy when creating icons and interfaces for Mac.