Procedural Asteroid

Step 1
The geometry
From the Get>Primitive>Polygon Mesh menu pick Icosahedron. Increase the Geodesic Frequency to 2. From the Modify>Deform menu pick Shape Jitter. In the Amplitude section of the PPG, change the X to about 4 and the Y and Z to about 3. (You can use the Seed slider to give each asteroid a unique shape). With the object still selected, chose Create>Poly.Mesh>Subdivision and set the Subdivision level to 3 to smoothen the asteroid.

Step 2
The shader tree
Apply a Lambert shader to the asteroid and press [7] to open the Render Tree. Get a Cloud node, two Cell nodes (both are found under Nodes>Textures), two Mix 2 Colors (Nodes>Mixers), a Color Corrector (Nodes>Image Processing) and finally a Change Range node (Nodes>Math). Connect all the nodes as seen on the above screenshot, and modify their respective settings accordingly.
Step 3
The craters
Open the Cloud PPG and in the Texture, click the New button and pick Spatial to apply a texture projection to the asteroid. Close the Render Tree. In the Main Command Area click the Selection button and from the menu click Geometry Approximation. Switch to the Displacement tab, change the Displacement Method to Fine and decrease the Length to 0.1. Your asteroid is now ready to be thrown in to space.

The project files used in this tutorial can be found at:
http://www.Redi-Vivus.com/Caffeineabuse/Procedural_Asteroid.zip