The ATLAS (Automatically Tuned Linear Algebra Software) project is an ongoing research effort focusing on applying empirical techniques in order to provide portable performance. It provides C and Fortran77 interfaces to a portably efficient BLAS implementation, as well as a few routines from LAPACK.
Argyll is an ICC compatible color management system. It supports accurate ICC profile creation for scanners, CMYK printers, and film recorders, and calibration and profiling of displays. Spectral sample data is supported, allowing a selection of illuminants observer types, and paper fluorescent whitener additive compensation. Profiles can also incorporate source specific gamut mappings for perceptual and saturation intents. Gamut mapping and profile linking uses the CIECAM02 appearance model, a unique gamut mapping algorithm, and a wide selection of rendering intents. It also includes code for a fast 8-bit raster color conversion engine as well as support for fast, fully accurate 16-bit conversion. Device color gamuts can also be viewed and compared using a VRML viewer.
Embedded File System (EFS) is a C++ library that allows you to create virtual file system in a single file. It can be useful when you need to create really big number of small files, as it is still fast even when you have millions of files. An encryption layer could be easily added for security.
The Lightweight Java Game Library is a native binding for OpenGL and OpenAL written with game developers in mind. It allows the full OpenGL and OpenAL APIs to be exposed without the penalties associated with competing methods, nor the limitations of APIs such as Java3D. Tutorials and demos are available, and Windows, Linux, and Mac OS X are supported.
MiGLayout is a versatile and flexible Swing and SWT layout manager. It uses string constraints or API type-checked constraints to format the layout. Strings are both short to type and easy to understand. MiGLayout can produce flowing, grid-based, absolute (with links), grouped, and docking layouts. It was created to be to manually coded layouts what Matisse/GroupLayout is to IDE-supported visual layouts.
NSFileHandleExt is an Objective-C extension (Cocoa/GNUstep) for the NSFileHandle class (which handles files/sockets). This extension provides support for much easier network programming for protocols like HTTP, IRC, telnet, etc. (everything that sends messages in lines suffixed by \n).
PACT is a self-contained set of tools which support developing and using portable programs, particularly scientific and engineering applications. By defining a single, higher level, standard programming interface, it shields application developers from the plethora of different hardware architectures and operating systems and their non-standard features.