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.
Ramona is an enterprise-grade runtime supervisor that allows software programs to be controlled and monitored during their execution life cycle. It provides supervisor/console functionality with init.d-like start/stop control, continuous integration (e.g. unit/functional/performance test launcher), deployment automation, and other command-line oriented features.
AmpJuke makes it possible to manage and stream your music online to several clients connected through a LAN or the Internet. In addition to streaming music, it can fetch "metadata" (album covers, images, lyrics, and track "fingerprints") automatically using various Web services such as last.fm and the.echonest. You can scan and import tags from as many tracks as you like, use favorites, and customize personal settings. Its focus is on easy navigation as well as speed.
PyParticles is a particle simulation toolbox entirely written in Python. It simulates a particle-by-particle model with the most popular integrations methods, including Euler, Runge Kutta, and Midpoint. It represents the results on an OpenGL or Matplotlib plot, and offers an easy-to-use API.