Af-Arch is an N-tier development framework to quickly build high-quality distributed applications. It currently supports C and C# programming languages, which enables you to write client applications using them. It currently runs on GNU/Linux and Microsoft Windows, and is being used in production environments.
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.
Aubit 4GL compiler is a programming language based on (and compatible with) Informix-4GL. It provides an easy way to generate screen/form based programs, since statements for handling Windows, Forms, Menus, SQL, and similar are built-in. With support for SQL statements forming an intrinsic part of the language, it's especially suitable for developing database-oriented applications. Database connectivity is provided for PostgreSQL, MySQL, Informix, and others via ODBC. It supports both ncurses (console mode) and GTK+ (GUI mode) output.
BBSzilla is an extension for Mozilla-based browsers such as the Mozilla Application Suite and Firefox. It gives the browser the ability to connect to Bulletin Board Systems that utilize TCP/IP, such as Hotline servers. There is functionality for multi-user chat, single-user messaging, as well as server-side and P2P file sharing, threaded news, single-thread bulletins, and more.