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.
Agent Farms is a system for modeling and simulation of complex, multi-agent based systems. The system can be used for creating models of multi-agent systems, interactive and distributed simulation, observation and visualisation of the simulation, and population modification and migration. On those models one can learn about the evolution of strategies in the populations of agents.
Display Ghostscript (DGS) is functionally upward-compatible with Adobe Display PostScript, but it has been written independently. The Display Ghostscript System provides a device-independent imaging model for displaying information on a screen. The imaging model uses the PostScript language which has powerful graphics capabilities and frees the programmer from display-specific details like screen resolution and color issues. DGS is an integral part of the GNUstep Development Environment.