CS::SkipList Library is a C++ template library of containers based on skip lists. These containers work like sets and maps, but can also be accessed via numerical index. This collection has vector-like containers where all operations work in logarithmic time. It also has a composite container where you can order the same elements in many different ways at the same time.
libpetey is a small scientific/numerical computation library. It includes the following components: templated sorting routines; templated binary tree classes; a templated linked-list class; routines for finding the k-least and k-greatest elements in an array; "supernewton", a one-dimensional root-finding algorithm based on cubic interpolation; a class for working with dates and times; a function for easy parsing of command line options; datasets (the beginnings of a data-representation paradigm that generalizes matrices but is mainly useful for n-dimensional linear interpolation); and sparse matrix library including command-line utilities for sparse matrix multiplication and eigenvalue decomposition as well as a sparse matrix calculator.
libKISSlog is a trivial lightweight C++ template library designed and written according to the KISS (Keep It Simple and Straightforward) principle. It leans heavily on STL for keeping its implementation as simple as its usage, and tries to provide C++ developers with a lightweight, paradigm-pure, and flexible alternative to logging libraries which use design and/or implementation decisions which at least the author of libKISSlog believes to be questionable. Its easiest to explain why libKISSlog would be suitable for your needs by listing the things which libKISSlog does not choose to use or do: no singletons or other forms of mutable global state, no macros, no attempt to fit the Java runtime everything model onto a C++ library, no attempt to be a Java-style (bloated) framework, no attempt to make the choice for you of whether you need thread safety, and no compromise on simplicity in order to facilitate questionable inner-loop logging practices.
libjmmcg is a basic, low-level library with pretensions to implementing features above and beyond (but not necessarily better than!) those implemented within the Standard C++ Library and the Boost Library. It features a library for multi-core or multi-chip SMP parallelism, a suite of hashing algorithms, functions for raising numbers to integer powers, a generic factory wrapper and a generic, multi-threaded, read-only cache (which uses PPD), arguably the world's worst sorting technique, trace output, exceptions that have the file, line, revision, function, and argument details, string utilities, logging, simple command line processing, and much more.