PC based Oscilloscope and Spectrum analyzer using sound card
FLO: a simple markup language to write flowcharts with any text editor
3D Charts - Templates for PovRay(TM)
GTK+iostream, Data plots, ORB, Neural Networks, WSOLA
A PHP class for creating graphs, plots, charts
Easy plotting of images pixel by pixel!
Audacity AudioMonitor (customized version of of Audacity 1.3-13-b).