ASCIIMathML is a script that converts calculator-style ASCII math notation (and many LaTeX formulas) to Presentation MathML while your Web page loads. It works with HTML and XHTML files in Mozilla/Firefox/Netscape 7+ browsers, as well as in Internet Explorer 6 with MathPlayer. For example, the solutions for the equation 'ax^2+bx+c=0' are expressed in the HTML file as '(-b +- sqrt(b^2 - 4ac))/(2a)', and display as nicely formatted MathML. The script can be easily used in wikiservers and blogs, as a rudimentary MathML editor (with instant preview), and to preview math formulas as they are typed into a Web page input area.
Algoscore is a graphical environment for algorithmic composition, where music is constructed directly in an interactive graphical score. The result is output to MIDI and CSound. Graphical objects are placed in a timeline and connected together. Some objects are fully dependent on user data, while some are generative and reacts on input from other objects. It is highly customizable and extensible with the Nasal scripting language. It has a non-realtime perspective where the composer can relate freely to time and construct the composition outside of time. This makes AlgoScore more like a traditional sequencer in this regard, but a graphical algorithmic sequencer with powerful and flexible scripting capabilities.
Allegro Sprite Editor (ASE) is a program specially designed with facilities to create animated sprites that can be used in some video game. It lets you create static images, characters with movement, textures, patterns, backgrounds, logos, color palettes, etc. It focuses on pixel editing to do pixel art. It isn't a photo retouching tool or a vector graphics editor. Mainly, it is a tool to create tiny animations pixel-by-pixel.
ArahPaint4 is a textile-oriented paint program, mainly for jacquard. It is a simple paint program for raster palette images. It has good tools for drawing images in repetition, support for handling palette images (color reduction, substitution, protected, transparent colors), contour tools, layer support, unlimited undo/redo, support for drawing in aspect ratio (pixels need not be square), a two level grid, and a coordinates display. It is simple, stable, fast, and works well on large images (>8000x8000).
AstroBuffer is a CCD astrophotography image manipulation application. It can open FITS and SBIG (st9) files. Contrast is adjustable to view different backgrounds and ranges of an image. It can scale, shift, rotate, and zoom in and out. Images can be aligned based on two star alignment, and can be summed, subtracted, averaged, and divided. RGB color images can be created from three images. Images can be saved as FITS or as any format that QT supports.
Asymptote is a powerful descriptive 2D and 3D vector graphics language for technical drawing, inspired by MetaPost but with an improved C++-like syntax. It provides for figures the same high-quality level of typesetting that LaTeX does for scientific text. Asymptote is a programming language as opposed to just a graphics program. It can exploit the best features of script (command-driven) and graphical user interface (GUI) methods. High-level graphics commands are implemented in the language itself, allowing them to be easily tailored to specific applications.
Audacity is a cross-platform multitrack audio editor. It allows you to record sounds directly or to import Ogg, WAV, AIFF, AU, IRCAM, or MP3 files. It features a few simple effects, all of the editing features you should need, and unlimited undo. The audio I/O uses PortAudio, which fully supports OSS, Mac OS X CoreAudio, and Windows WMME, and can be compiled with support for ALSA and Jack.