The Interface Window Manager uses Objective C and the GNUstep libraries to provide strictly minimal functionality, with all additional features in bundles called IWMComponents. It uses the GNUstep defaults database for user settings such as mouse button configuration, key bindings, and initial color settings, and is optimized for use in a strictly GNUstep environment.
X Resource Graph (XRG) is a system monitor that shows graphs for CPU usage, memory usage, battery status, machine temperature, network usage, disk usage, current weather, and stock market data. It is designed to use as little overhead possible while showing a lot of information about the resource usage in a nice interface.
XShelf is an application that enhances Drag and Drop operations in MacOS X by providing a shelf where drag-and-dropped items (such as files, text, or URLs) can be stored for later use. Thus, not only can Drag and Drop operations be "paused", multiple operations can be in flight at once. It is the spiritual heir to the NeXT Shelf.
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.