Microsoft's DirectX Software Development Kit
Windows SDK Download
This is the complete download of Microsoft's Windows SDK. It was previously known as the Platform SDK.
An open source programming library for including XML parsing in your applications.
Novell's Open Source initiative for a platform independent implementation of the .NET framework.
This is the free open source implementation of STL, which provides perhaps the most portable version of the library.
A free comercial quality networking library, designed with multiplayer games in mind.
Boost C++ Libraries
This is the official page for the boost C++ libraries.
SAX - Simple API for XML
An event based approach to reading XML documents. It is much more efficient than the more wellknown DOM method, but it can also be a bit more complicated to work with.
SFML - Simple and Fast Multimedia Library
zlib open source, cross platform, light-weight library for doing various low and high level tasks: windowing, audio, input, networking, graphics, etc. SDK is based on separate classes so it's possible to use parts of the library if that's what's desired.
POCO C++ Libraries
Free C++ library for performing common tasks.
PCRE - Perl Compatible Regular Expressions
A C library that implements a regular expression engine that can be embedded in applications and script engines.
Recast & Detour
A tool kit for pathfinding. Includes a tool for building navigation meshes as well as a library to do pathfinding in it.
This is an open source math and geometry library for C++. Besides having a lot of useful classes and functions, the site also has a lot of links to other resources on related subjects.