I'm writing a program to generate some trippy visuals. My code paints each pixel with a random blue value which loops at 0.04 second intervals.

for (y = 0; y < 5.5; y += 0.2) {
    for (x = 0; x < 7.5; x += 0.2) {
        b = rand() / ((double) RAND_MAX);
        setPixelColor(x,y,r,g,b);
    }
}

I'd like to do more than just make blue noise... but my maths is a bit rusty, and Google isn't helping me much today, so it would be great if you could share anything you know about making waves, patterns, gradient animations, etc or links to such material.