Nickel is a library for hierarchical maps and .ini files. It can be used to easily read, manipulate, and write configuration data in .ini format, among other things. It's also handy wherever a map structure (or tree of maps) is called for. Nickel focuses on speed, robustness, and portability.
HappyHTTP is a simple C++ library for issuing HTTP requests and processing responses. It is simple to integrate: just drop in the .h and .cpp files. It has an easy-to-use interface, non-blocking operation (suitable for use in game update loops), and pipelining support (you can issue multiple requests without waiting for responses).
Intlize allows the developer to use catgets without its normally bulky syntax and without having to mind the details of correct indices. Catgets is the built-in internationalization suite of C compilers. Alternatively, Intlize can produce a compact file format optimized for fast access. Intermediate files are in gettext po format, so there are many comfortable tools available to do the translations. Runtime files are provided for C and C++ and for both catgets and intlize native support.
XIDEK is an extensible interpreter development kit. It supports an interpreter and simple compiler development with a small but complete collection of reusable, extensible parsing and support modules. These modules implement standard expression and statement syntax, including control statements, symbol tables, abstract syntax trees, and simple bytecode interpreters. They can be used as a starting point for rapid development of language processors for script languages, "little languages", or domain-specific languages. Numerous documented examples show how to combine and extend the base modules into custom interpreters.
SQLpp is an SQL query generation framework for C++ and .NET. Its main features are .NET assembly, automatic SQL code generation, multiple database support, solving table joins puzzles, support for update, insert, and select queries, C# class wrapper generation (generates an entire Data Abstraction Layer), generation of a DAL for DotNetNuke or your application, Graphviz database representation generation, and smart stored procedure generation.