perlineditor

Perlin noise is a form of noise with local coherence. It's used in creating all kinds of graphics, from wood efffects to marble. The editor lets you create an image with Perlin noise interactively, and save it as a gif. You can change the noise parameters, and you can edit the palette, either loading it from a gif, or using the palette editor (right click to open the color picker, left click to move the two selection points about). There's also a handy tool for tuning the palette as the image adjusts (drag on the red circle to adjust, the black circles to move the edit range).