BRL-CAD is a powerful constructive solid geometry solid modeling system that includes an interactive geometry editor, ray-tracing support for rendering and geometric analysis, path-tracing for realistic image synthesis, network distributed framebuffer support, and image and signal-processing tools.
The Model Railroad System is a software package that can help you run your railroad. It allows you to operate your layout, from running trains to working your signals and switches. It has support for a network of Bruce Chubb CMR/I USIC, SUSIC, and/or SMINI nodes, and/or a network of Lenz's XPressNet DCC nodes. Azatrax USB-connected Model Railroad Detectors are supported. Software to create switch lists for freight car forwarding and create timetables for your railroad are included. There is software to help with photographing your trains, and to compute the correct value for those pesky dropping resistors for LEDs and/or incandescent lamps.
Xapian is a search engine library, scalable to collections containing hundreds of millions of documents. It's written in C++ with bindings for Perl, Python, PHP, Java, Tcl, C#, Ruby, and Lua. It is a highly adaptable toolkit that allows developers to easily add advanced indexing and search facilities to their own applications. It supports the Probabilistic Information Retrieval model and also a rich set of boolean query operators. Omega is a Web search application built upon the Xapian library. It can index a Web server's document tree (including HTML, PDF, OpenOffice, MS Word/Excel/Powerpoint/Works, WordPerfect, RTF, PS, etc.), or data exported from arbitrary sources (e.g. SQL databases).
Berkeley DB (libdb) is a programmatic toolkit that provides embedded database support for both traditional and client/server applications. It includes b+tree, queue, extended linear hashing, fixed, and variable-length record access methods, transactions, locking, logging, shared memory caching, database recovery, and replication for highly available systems. DB supports C, C++, C#, Java, PHP, and Perl APIs. It supports key-value pair (NoSQL), SQL, and Java Object formatted data. It is available for a wide variety of Unix platforms as well as QNX, Android, Mac OS X, and several varieties of Windows.
IRRToolSet is a set of policy analysis tools, written in C++. It's designed to run under UNIX, using Tcl/Tk for graphics. There are tools for generating router configuration files, displaying and checking routes, generating aggregations of networks, etc. This project was formerly known as the Routing Arbiter ToolSet (RAToolset), and was maintained by ISI.
The pilot-link suite of tools contains a robust library and a series of conduits for moving information between your desktop or workstation and your Palm handheld device, such as those made by Palm, Sony, Handspring, Handera, and others. It also includes language bindings for languages such as Perl, Python, and Java.
The GOBLIN project consists of a C++ class library for a large series of graph optimization problems, GOSH, an extension of the Tcl/Tk scripting language to graph objects, and GOBLET, a graphical user interface to the library functions. GOBLET includes a graph editor and supports the standard graph layout methods.