XML-RPC is a spec and a set of implementations that allow software running on disparate operating systems, running in different environments to make procedure calls over the Internet. It's remote procedure calling using HTTP as the transport and XML as the encoding. It's designed to be as simple as possible, while allowing complex data structures to be transmitted, processed and returned. Currently there are implementations (differing in maturity) for Frontier, Python, Java, Perl, Tcl, ASP and PHP.
Zune is a free clone of the famous MUI (Magic User Interface) toolkit from the Amiga. It is primarily designed for C, and uses BOOPSI as an object-oriented layer. The MUI-apps developer should not care about "precise" graphic design (to let the user fully customize its application), and not care about resize (smart automatic layout algorithm). The MUI-apps user has maximum control over applications look and feel, and he can customize apps either globally or individually through a graphical prefs program.
The Revision Control System (RCS) manages multiple revisions of files. RCS automates the storing, retrieval, logging, identification, and merging of revisions. RCS is useful for text that is revised frequently, for example programs, documentation, graphics, papers, and form letters.
Leaky can help you track down memory leaks and some kinds of memory corruption. It also has entry pointers for logging addref / release calls. The key thing that leaky does is this: it logs all calls to malloc / free / realloc / new / delete into a log file. The logging data includes information about size and address, as well as the call stack of the operation. The leaky program then can translate the call stack data from addresses into symbols and then dump the data out.
KDOC is a C++ and IDL interface documentation tool, initially written for the specific purpose of generating documentation for the KDE libraries. It extracts specially formatted documentation and information about your classes from the class' header or IDL files, and generates cross-referenced HTML, LaTeX or Man pages from it. KDOC allows groups of classes to be formed into "libraries" and documentation from separate libraries can be very easily cross-referenced.
V is a free portable C++ GUI Framework intended to develop a wide variety of applications on different graphical interface platforms. It is very complete and suitable for a large majority of custom GUI applications. Applications developed using V will have the look and feel of the native platform, yet will be portable across platforms. Current platforms include MS-Windows WIN32, X Athena, X Motif, X gtk, and OS/2.
Rioja is a record-oriented java input/output class library. It is 100% Pure Java and allows Java applications, on any Java platform, to work with binary records in files on multiple file systems. Using Rioja, a developer can sequentially scan, append, overwrite, and update records in record-oriented files, and list, create, rename, and delete files in multiple file systems.
libwayne is a library of reasonably abstract datatypes and algorithms written in C. They have a consistent user interface. Many of the algorithms are taken verbatim from textbooks, but are coded well. The library contains data structures and code for binary trees, stacks, queues, combinatorial analysis, bit strings, graphs, dynamic arrays, event-driven simulation, priority queues, about half a dozen different O(n log n) sorting algorithms, ODE integration, long long integer I/O, matrix and vector operations, random number generation, search algorithms, and elementary statistics.