Algorithm::Diff is a Perl module for computing the difference between two files, two strings, or any other two lists of things. It uses an intelligent algorithm similar to (or identical to) the one used by the Unix `diff' program. It is guaranteed to find the smallest possible set of differences.
Allegro is a multi-platform game library for C/C++ developers that provides many functions for graphics, sounds, player input (keyboard, mouse, and joystick), and timers. It also provides fixed and floating point mathematical functions, 3D functions, file management functions, compressed datafile, and a GUI.
The Advanced Linux Sound Architecture is composed of several parts. The first is a fully modularized sound driver which supports module autoloading, devfs, isapnp autoconfiguration, and gives complete access to analog audio, digital audio, control, mixer, synthesizer, DSP, MIDI, and timer components of audio hardware. It also includes a fully-featured kernel-level sequencer, a full compatibility layer for OSS/Free applications, an object-oriented C library which covers and enhances the ALSA kernel driver functionality for applications (client/server, plugins, PCM sharing/multiplexing, PCM metering, etc.), an interactive configuration program for the driver, and some simple utilities for basic management.
ANGIF is a C library to generate GIF format output. It can generate animated GIFs or true-color (24-bit) GIFs (using both at the same time, however, does not display properly on common browsers). ANGIF is completely LZW-free. There is no code implementing the patented LZW algorithm. That also means there is no compression and the files will actually be larger than a raw file with the same image by about 13% to 16% more. Command line level test programs are included. This is a quick rough-cut beta version with documentation only in the source code (the source code actually is commented).
Apache Jakarta Regexp is a 100% pure Java regular expression package. Expression syntax supports all of Perl5 syntax, with the exception of back reference substitution markers (several people have mentioned this lack, so please feel free to contribute a solution). It also supports a very limited subset of POSIX features. Performance and features are somewhat inferior to ORO, and the new JDK 1.4 (java.util.regex) package, but the package is especially small and features the ability to precompile expressions (without using object serialization) into byte arrays, thus avoiding the need to load the expression compiler.
Apache::Session is a persistence framework whose purpose is to provide session management to Web developers. It is designed to work with Apache and mod_perl, but it does not depend on them and will work with any Web server. This module provides a set of classes that give the developer maximum functionality. Session data can be stored in a database, flat files, or shared memory.
'App' is a preprocessor for C++ that accepts as input arbitrary C++ code that may contain embedded constructs for specifying algebraic data types and associated pattern matching operations, and produces as output the same code with all such constructs translated to normal C++. What app essentially does is provide for C++ pretty much the same capabilities that functional languages have regarding algebraic types. 'Applib' is the associated runtime library that supports the core run time requirements of the translated code, and which provides additional utilities (applib is covered by the LGPL).