Awesome

JBShellView

This class provides a shell or command-line interface. Some features:

• Cocoa native, it's an NSTextView subclass
• Supports command history, so you can use up and down arrows, as you'd expect
• Supports auto-pairing for smarter text editing via JBTextEditorProcessor
• Supports asynchronous operations so you don't hang the interface.

Demo

The demo application shows off the Shell view and lets you enter commands. The only recognized command is search some query, but by checking out the app you can hopefully figure out how to support different commands. It's pretty straightforward.