StackApps comes bundled with a couple of example apps that can be used to learn how to use StackApps and learn about the more sophisticated features of the product.
MyTasks is a very basic StackApps project to manage simple tasks that contains all the ingredients of a minimal CRUD based app:
Inventory adds a couple of new features to what we've learned via the MyTask app:
The CMS project covers the content management capabilities of StackApps. Using various CMS Stacks you can display database content on your site either in the regular content area or in a arbitrary ExtraContent area. The project also includes a content editor that can be linked to the actual content.
This is the most complex app example that creates a basic blog that uses the themes blog styles that are usually bundled with RapidWeaver themes. The blog features: