GTK/GTK+ or Gimp ToolKit, is a GNU library for creating graphical user interfaces.
As implied by the name, the Gimp Toolkit was originally created for the GIMP image editor. It has since become one of the leading GUI toolkits for X, along with Qt, both of whom succeed Motif. GTK is generally favored by those who develop for Gnome, and Qt is favored for KDE. The reason for this is that GNOME uses GTK+ as a base toolkit, and KDE uses Qt.
GTK+ is written in C, and provides bindings for C++ and Java, as well as the scripting languages Perl and Python (PyGTK). Other language bindings are available as well through third party bindings.
Developers using GTK+ can pick between various display engines that give GTK+ apps a wide variety of looks, from the old Motif style to the GTK+ standard look.
GTK+ applications are generally fairly portable, and can run outside of GNOME, on platforms such as Windows as well as KDE.
GTK+ 2 is the version 2 release of GTK+ that includes general improvements in many areas, but breaks compatibility with GTK+ 1. These improvements include better support for Unicode, accessibility improvements, and changes to the API to improve flexibility. These improvements however come at the cost of speed and simplicity, and many developers continue to use GTK+ 1.
qooxdoo is a comprehensive and innovative Ajax application framework. Leveraging object-oriented JavaScript allows developers to build impressive cross-browser applications. No HTML, CSS nor DOM knowledge is needed.
It includes a platform-independent development tool chain, a state-of-the-art GUI toolkit and an advanced client-server communication layer. It is Open Source under an LGPL/EPL dual license.
toolkit
Ajax
JavaScript
License:LGPL
GUI-Toolkit
opensource
Framework
gui
Library
epl
opensource: del.icio.us tag/opensource
Library
JavaScript
opensource
License:LGPL
system:has:license
opensource: del.icio.us tag/opensource
Security
Library
PHP
opensource
XSS
License:LGPL
system:has:license
JRecord is a Java project that provides code to read and write Cobol Files and Files with length based records (some times used by Cobol). It contains code used by RecordEditor to read and write files.
Java
cobol
Library
RecordEditor
License:LGPL
bruce-martin
jrecord
X is a a collection of loosely-bound, cross-browser, Javascript functions and objects. It is intended to be a resource from which you pick and choose – you do not have to include the entire library in your application. It contains core DOM/Style functions, unobtrusive enhancements, utility functions, objects such as menus and tab panels, and also has some experimental stuff. I’ve been developing this library since 2001 (I started its predecessor around 1999). Thanks to thousands of people like yourself X has been extensively tested on a wide range of operating systems and browsers. Thanks to your contributions X continues to improve, grow and evolve.
The X Library is distributed under the terms of the GNU LGPL.
Users are encouraged to submit feedback and/or code to improve the library itself or its compatibility with various web browsers.
X-Library
User:mikefoster
License:LGPL
widgets
cross-browser
dhtml
JavaScript
Library
Ajax
Framework
PHP Tag Engine is a library for PHP to add tagging to a PHP application, with Ajax support that includes autocompleting tags.
PHP Tag Engine caches tag data to reduce database strain, and the library is fully utf-8 compatible and documented through the PHP Doc format.
DO YOU REALLY WANT TO ENABLE PUBLIC EDITING ON THIS WIKI?
A Cross-browser JavaScript DHTML Library which adds Drag Drop functionality and extended DHTML capabilities to layers and to any desired image, even those integrated into the text Drag & Drop Image flow.
Library
Programming
JavaScript
dhtml
License:LGPL
Walter-Zorn
wz_dragdrop
PPTactical is a 2d engine for real-time strategy and real-time tactics games
Development
License:LGPL
Real-Time-Strategy
Game-Engine
code
games
C++
game
Library
PPTactical

The FileHelpers are an easy to use .NET library written in C#. Is designed to read/write data from flat files with fixed length or delimited records (CSV). Also has support to import/export data from different data storages (Excel, Access, Sql Server)
The library has a set of converters for the basic types and can be easily extended to provide custom converters.
The Basic Idea:

Using the library with other DataStorages

filehelpers
Marcos-Meli
License:LGPL
Fixedlength
Delimited
flatfile
csv
C#
.NET
Library
JSXML includes REXML, a high-performance parser that doesn’t mind if you throw 2000 lines of (well-formed) XML at it, a builder with a unique API that invites the coding of GUIs (graphical user interfaces) around it, and an iterator that makes costly recursion unnecessary.
jsxml
Library
xml
parser
JavaScript
regex
REXML
License:LGPL
Level-Three-Solutions
DynaMo is a software library providing classes that take care of the calculation of the motions of objects under the influence of force, torque, and impulse. It can also compute forces for you through the mechanism of constraints.
HTML_Ajax is a PHP library in PEAR for JavaScript/AJAX.
Ajax
Library
PHP
JavaScript
php-library
pear-package
License:LGPL
HTML_Ajax
Textbreak is an under development project that is intended to make universal word segmentation library for any natural language
Library
natural-language
word-segmentation
License:LGPL
Vee-Satayamas
Banlu-Kemiyatorn
textbreak
Libgcrypt is a general-purpose cryptographic library based on the code from GnuPG.
It provides functions for all cryptographic building blocks: symmetric ciphers (AES, DES, Blowfish, CAST5, Twofish, and Arcfour), hash algorithms (MD4, MD5, RIPE-MD160, SHA-1, and TIGER-192), MACs (HMAC for all hash algorithms), public key algorithms (RSA, ElGamal, and DSA), large integer functions, random numbers, and a lot of supporting functions.
The Audio File Library provides a uniform and elegant API for accessing a variety of audio file formats, such as AIFF/AIFF-C, WAVE, NeXT/Sun .snd/.au, Berkeley/IRCAM/CARL Sound File, Audio Visual Research, Amiga IFF/8SVX, and NIST SPHERE.
Supported compression formats are currently G.711 mu-law and A-law and IMA and MS ADPCM.
GStreamer is a streaming media library and set of tools.
These tools enable applications to share a common set of plugins for things like video decoding and video encoding, audio encoding and decoding, audio and video filters, audio visualisation, Web streaming and anything else that streams in real-time or otherwise.
SDL is a library that allows you portable low-level access to a video framebuffer, audio output, mouse, and keyboard.
OpenAL, the Open Audio Library, is a joint effort to create an open, vendor-neutral, cross-platform API for interactive, primarily spatialized audio.
JFreeChart is a chart library for the Java platform that supports a wide range of charts including pie charts (2D and 3D), bar charts (horizontal and vertical, regular or stacked, with optional 3D-effects), line charts, XY plots, scatter plots, time series charts, high/low/open/close charts, candlestick plots, Gantt charts, Pareto charts, combination charts, and more.
Sarissa is a Javascript API which encapsulates XML functionality in browser-independent calls.
Sarissa is an ECMAScript library acting as a cross-browser wrapper for native XML APIs. It offers various XML related goodies like Document instantiation, XML loading from URLs or strings, XSLT transformations, XPath queries etc and comes especially handy for people doing what is lately known as “AJAX” development.
Supported browsers are Mozilla – Firefox and family, Internet Explorer with MSXML3.0 and up, Konqueror (KDE 3.3+ for sure), Safari and Opera. Konq, Safari and Opera offer no XSLT/XPath scripting support AFAIK.
Docs http://sarissa.sourceforge.net/doc/
JavaScript
Ajax
License:LGPL
License:GPL
Sarissa
api
XSLT
xml
Library
ECMA