The SOPE package is an extensive set of frameworks (16 frameworks, ~1500 classes) which form a complete Web application server environment. Besides the Apple WebObjects compatible appserver extended with Zope concepts, it contains a large set of reusable classes: XML processing (SAX, DOM, XML-RPC), MIME/IMAP4 processing, LDAP connectivity, RDBMS connectivity, and iCalendar parsing. The parts of the package can be used stand-alone (e.g. in Cocoa applications) and do not require the appserver parts. For MacOSX developers, the package includes SOPE:X, which contains special Xcode and Cocoa support for SOPE.
JIGS (Java Interface for GnuStep) allows Java programmers to use the GNUstep libraries from Java, but it is more than a set of bindings for GNUstep from Java: it takes advantage of the fact that Objective-C and Java are very similar languages to make it possible to use Objective-C classes from Java using exactly the same API (and vice versa). Moreover, JIGS can generate automatically wrappers for your own Objective-C GNUstep libraries.
Tk Drag and Drop is an extension for Tcl/Tk to add native drag and drop capabilities to the Tk toolkit. It is designed for Tk versions 8.3.3 and higher. Native drag and drop are supported under Microsoft Windows (XP, Vista, 7), Mac OS X Leopard (Cocoa framework), and Linux (XDND, drag support missing).
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.