Some code snippets/projects which may be of interest. I'm certainly no expert.
ASScriptMenuManager is an Objective-C class which creates an AppleScript menu for your Cocoa application as in the picture below. It's very simple to use. Download a small demo project which includes the class files and a ReadMe which describes how to use ASScriptMenuManager.
CocoaAccessorWriter source code
Here's a link to the source for CocoaAccessorWriter: CocoaAccessorWriter Xcode project.
If you'd just like to use CocoaAccessorWriter and don't want the source, click here.
Read about CocoaAccessorWriter here.