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).
Lua is a great programming language that prides itself on ANSI C portability, small size, simplicity, and ease of embedding. Due to these goals, the official Lua distribution cannot provide features common to popular stand-alone scripting languages. The goal of the LuaCheia project is to make a full-featured language based on Lua that makes it more usable as a stand-alone language.
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.