cso is an easy to use C module that serializes objects into a simple binary format. It can be used to store data or to send it over a network. It supports either an object of type struct (CSO_DICT) or array (CSO_ARRAY) which contains elements of type integer of different sizes, double, binary, string, struct, or array.
h2incn tries to directly convert C/C++ headers to Nasm-style include files, and can be used in a makefile. It is useful if you want to use the same structures or external variable declarations in C and assembler code, and you don't want to use two separate files and update both each time you change something. It is written in a mix of C and C++ code. It currently works for simple files.
Slate is a prototype-based object-oriented programming language based on Self, CLOS, and Smalltalk. Slate syntax is Smalltalk-80-based, rather than trying to be clever and complex. However, the language semantics, environment, and run-time design are all much more powerful than in traditional Smalltalk systems. The design goal is to bring together many excellent existing ideas into one system, and to provide an environment where design decisions in one area don't constrain others.
CDuce is a programming language adapted to writing safe and efficient applications that manipulate XML documents. A type system checks at compile time that applications deal with all the possible inputs and produce only valid outputs. Pattern matching is a powerful operation based on regular expressions to inspect documents. CDuce also features general-purpose features; it is a higher-order functional language, with a type-safe interface with Objective Caml.
epto is a small library and framework for industrial strength shell script programming with sh. It features convenient error handling, tracing, logging, option handling, documentation template, process level transaction safety (sort of), and more. If one is used to shell programming, it takes less than five minutes of learning to start using it (see the crash course in the README file).
Xsel is a quick hack to give access to the X selection from the command-line. You can then copy stuff between stdin/stdout and the X selection buffer. For example, 'echo puppa | xsel -c' makes "puppa" the current X selection. 'xsel -p | less' pastes the current X selection to less.