These are some of the great Third Party Developer Tools out there for Cocoa developers. I've used these on mostly a daily basis and others on an as needed basis. They're very handy and have saved me quite a lot of time and typing. Hopefully they'll be as useful to you, as they have been for me.

1. Accessorizer - Code generation for pretty much everything you'll ever need in Cocoa development.
2. IConify - Drag in an image and it'll generate the icon files for your iOS app. XCode comes with Icon Composer which can help as well.
3. App Scanner - scans your app for private API calls, so you can check before you submit it to the App Store for review.
4. Localization Suite - Everything you need to get your Cocoa app localized, minus someone to actually translate the words and phrases.
5. Code Pilot - Quick project navigation through files
6. Ingredients - Cocoa Documentation Viewer

Some are free, others are not.