I'm new! Mandelbulb & IFS's

[Deliverance]

Hi guys! I'm new here here so a big hello to everyone!

Now, let's go straight into the business. Yesterday i started my adventures into exploring the mandelbulb. Obviously i ran into some problems. First there is the speed: i'm ray marching constant steps and iterate over the formulas to see if i'm inside or not. How can this be improved?

Second there is coloring: i managed to get normals but it looks kind of dull with phong shading and ramp coloring. How can i do better?

Here are two pictures of the beast:
http://img8.imageshack.us/i/mandelbulbimg2.png/
http://img156.imageshack.us/i/mandelbulbimg.png/

And here is the GLSL shader code, for reference:

Code:

varying vec3 position;
uniform float time;
uniform sampler2D spectrum;
int maxiter = 6;

vec4 getMandelbrot(vec3 posInit)
{	
	posInit *= 1.95;	

	//posInit.x -= 1.15;	
	//posInit /= 2.0;	
	
	vec3 pos = posInit;
	int n = 8;
	int i;
	
	for (i=0; i<4; i++)
	{	
		float r = length(pos);
		
		if (r > 2.0)
			return vec4(pos, 0.0);			
		
		float theta = atan2(length(pos.xy), pos.z);
		float phi = atan2(pos.y, pos.x);
	
		float pown = pow(float(r), float(n));
				
		pos.x = pown * sin(theta*n) * cos(phi*n);
		pos.y = pown * sin(theta*n) * sin(phi*n);
		pos.z = pown * cos(theta*n);			
		
		pos += posInit;
	}

	return vec4(pos, 1.0);			
}

vec3 rotateX(vec3 pos, float angle)
{
	vec3 ret;
	ret.x = pos.x;
	
	ret.y = cos(angle)*pos.y - sin(angle)*pos.z;
	ret.z = sin(angle)*pos.y + cos(angle)*pos.z;

	return ret;
}
int numIterations = 128;
vec4 marchRayMandelbrot(vec3 pos)
{
	int i = 0;
	vec3 dir = vec3(0.0, 0.0, 2.0);
	
	float angle = time / 8;
	
	dir = rotateX(dir, angle);
	pos = rotateX(pos, angle);
	
	vec3 inc = 1.0 / float(numIterations) * dir;
	vec3 start = pos;
	vec3 end = pos+dir;	
		
	for (i=0; i<numIterations; i++)
	{				
		vec4 a = getMandelbrot(pos);	
		if (a.w != 0.0)		
		{		
			a.w = i;
			return a;
		}
		pos += inc;
	}	
	
	return vec4(0.0,0.0,0.0,0.0);
}

void main()
{	
	float eps = 0.01;	
	gl_FragColor = 0.0;	
	vec3 lightPos = vec3(0.0,0.0,10.0);

	vec4 a = marchRayMandelbrot(position);
	
	if (a.w > 0.0)
	{
		float len = length(a.xyz);
		
		vec4 a1 = marchRayMandelbrot(position + vec3(eps, 0.0, 0.0)) - marchRayMandelbrot(position - vec3(eps, 0.0, 0.0));
		vec4 a2 = marchRayMandelbrot(position + vec3(0.0, eps, 0.0)) - marchRayMandelbrot(position - vec3(0.0, eps, 0.0));
		vec4 a3 = marchRayMandelbrot(position + vec3(0.0, 0.0, eps)) - marchRayMandelbrot(position - vec3(0.0, 0.0, eps));	
		
		a1 /= 2*eps;
		a2 /= 2*eps;
		a3 /= 2*eps;
		
		vec3 norm = vec3(length(a1.xyz), 
						 length(a2.xyz),
						 length(a3.xyz));
		
		norm = normalize(norm);	
		
		vec3 lightDir = normalize(lightPos - a.xyz);		
		vec3 view = -normalize(a.xyz);
		float diff = 0.35+0.5*max(0.0, dot(norm, lightDir));
		
		float spec = 0.0;
		if (diff > 0.0)
		{
			spec = max(0.0, pow(dot(normalize(lightDir+view), norm), 64.0));
		}
		
		//gl_FragColor = vec4(0.0, 1.0, 0.0, 0.0)*diff*0.8+spec;	
		gl_FragColor = spec + diff*texture2D(spectrum, vec2(a.w / numIterations, 0.0));
		//gl_FragColor = 1.0;
	}
	
}

And third there are IFS's. Where can i get some starting functions that would produce nice images? I managed to display the sierpiensky triangle but nothing interesting comes from my playing with different functions.