This is a handy little library which provides a packet filtering mechanism based on the BSD packet filter (BPF). Most notably, tcpdump needs this to work, and there is also a perl module (still in beta) which can use this as well. In plain english, if you want to write your own network traffic analyzer, this is the place to start.
Dante is a free implementation of the proxy protocols SOCKS version 4 and SOCKS version 5 (RFC 1928). It can be used as a firewall between networks, controlling outgoing traffic. The package consists of two parts: a socks server and a proxy client that supports socks, HTTP proxies, and UPnP. RFC 1961 (GSSAPI) is supported in both the client and the server. Commercial support is available.
CFITSIO is a library of C and Fortran subroutines for reading and writing data files in the FITS (Flexible Image Transport System) data format. It simplifies the task of writing software that deals with FITS files by providing an easy to use set of high-level routines that insulate the programmer from the internal complexities of the FITS file format.
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.
ViewVC (formerly known as ViewCVS) is a Python/CGI-based system for viewing and interacting with Subversion and CVS repositories through your Web browser. It can browse directories, view changelogs, generate diffs, view arbitrary revisions, and display annotated ("blame") listings. It has full support for tags and branches, and contains a database-backed query system like Bonsai. It was initially based on the cvsweb work by Henner Zeller, but has been ported to Python and dramatically enhanced.
xmlrpc-c is a programming library for writing an XML-RPC server or client in C or C++. XML-RPC is a standard network protocol to allow a client program to make a simple remote procedure call (RPC) type request of a server. It's like SOAP or CORBA, but much simpler. This library speaks the same XML-RPC as similar libraries for lots of other programming languages, with most of the popular extensions. The client library uses either w3c libwww or Curl for HTTP. The server library contains a complete lightweight HTTP (Web) server and also facilities for running with CGI under any Web server.
FreeMarker is a template engine that was originally designed so that servlet-based applications could keep graphical design separate from application logic. The templates provide an easy and highly flexible way to generate any kind of text output (HTML, PostScript, TeX, source code, etc.) from a variety of data sources such as Java objects, Jython objects, XML object models, and more.