Metakit is a small, portable database library using a hybrid relational / hierarchical data model with a column-wise internal storage format. For C++, include a single header file and 125 kb DLL or statically link directly. Ideal for desktops, embedded systems, smartphones, and PDAs. Bindings for Python and Tcl. A very mature, stable code base.
txtorcon is a Twisted-based asynchronous Tor control protocol implementation. Twisted is an event-driven networking engine written in Python, and Tor is an onion-routing network designed to improve people’s privacy and security on the Internet. It includes unit-tests with 96%+ coverage, multiple examples, and documentation. There are abstractions to track Tor configuration and state (circuits, streams), launch private instances, support Hidden Service, and more.
Pyramid is a small, powerful, and flexible set of Web development components that supersedes both Pylons 1. 0 and repoze.bfg. It can be used to write clean and fast applications, and supports plugging in a variety of components like storage, templating engines, and authentication mechanisms.
EO is a template-based, ANSI-C++ evolutionary computation library that helps you to write your own stochastic optimization algorithms quickly. Evolutionary algorithms form a family of algorithms inspired by the theory of evolution, and solve various problems. They evolve a set of solutions to a given problem in order to produce the best results. These are stochastic algorithms because they iteratively use random processes. The vast majority of these methods are used to solve optimization problems, and may be also called "metaheuristics". They are also ranked among computational intelligence methods, a domain close to artificial intelligence. With the help of EO, you can easily design evolutionary algorithms that will find solutions to virtually all kind of hard optimization problems, from continuous to combinatorial ones.