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.
DigitizeIt digitizes scanned graphs and charts. Graphs can be loaded in nearly all common image formats (including gif, tiff, jpeg, bmp, png, psd, pcx, xbm, xpm, tga, pct), pasted from the clipboard, or imported via a screenshot. Digitizing of line and scatter plots occurs automatically, and manual digitizing via mouse clicks is also possible. Data values are transformed to a specified axes system and can be saved in ASCII format, ready to use in many other applications such as Microcal Origin or Excel. Axes can be linear, logarithmic, or reciprocal scale. Multiple data sets can be defined and edited. Tilted and distorted graphs can be handled. Comprehensive online help is included. Java 1.4 is required.
LAoE is a graphical audiosample-editor, based on multi-layers, floating-point samples, volume-masks, variable selection-intensity, and many plugins suitable to manipulate sound, such as filtering, retouching, resampling, graphical spectrogram editing by brushes and rectangles, sample-curve editing by freehand-pen and spline and other interpolation curves, effects like reverb, echo, compress, expand, pitch-shift, time-stretch, and much more.
Tux Paint is a simple and entertaining drawing program geared towards young children. It has a simple interface, sound effects, and a cartoon character (Tux, the Linux penguin). Along with drawing brush strokes, lines and shapes, you can also enter text and place "rubber stamp" (or "sticker") images on the picture. Tux Paint is extensible, and could be useful in an educational environment (such as a grammar, elementary, or grade school). It's portable across numerous platforms, and runs well even on slower systems like the Pentium 133MHz.