Boost provides free peer-reviewed portable C++ source libraries.

http://www.boost.org/

Boost provides free peer-reviewed portable C++ source libraries.
We emphasize libraries that work well with the C++ Standard Library. Boost libraries are intended to be widely useful, and usable across a broad spectrum of applications. The Boost license encourages both commercial and non-commercial use.
We aim to establish "existing practice" and provide reference implementations so that Boost libraries are suitable for eventual standardization. Ten Boost libraries are already included in the C++ Standards Committee's Library Technical Report ( TR1) as a step toward becoming part of a future C++ Standard. More Boost libraries are proposed for the upcoming TR2.
Getting started: Boost works on almost any modern operating system, including UNIX and Windows variants. Follow the Getting Started Guide to download and install Boost. Popular Linux and Unix distributions such as Fedora, Debian, and NetBSD include pre-built Boost packages. Boost may also already be available on your organization's internal web server.
Background: The Background Information page has introductory material to help those educating their organization about Boost.