Addresses is a GNUstep address book that consists of a full-featured address book manager application, a source-code compatible replacement for Apple's AddressBook.framework (for accessing and manipulating address data programmatically), a framework of view/editor classes that make it easy to use Addresses from your own programs, and a number of tools. It is easy to use by both users and programmers and can store almost all imaginable data, including multiple phone numbers, emails, and addresses, photos, AIM/Jabber/ICQ/Yahoo IM details, and notes. It supports drag-and-drop and integrates well with GNUMail.
CUT is a unit-testing framework for C, C++, and Objective-C. Unlike other unit testing tools, CUT doesn't strive to be an SUnit clone. It automates a lot of the drudge work often encountered when using other unit testing packages for the C family of programming languages. CUT may also be used to unit-test assembly language software in some circumstances.
CocoaDialog is an application that allows the use of common GUI controls such as file selectors, text input, progress bars, yes/no confirmations, and more from within a command-line application. It requires no knowledge of Cocoa, and is ideal for adding front-ends to shell, Perl, Ruby, or Python scripts.