Well, I can throw these together pretty quick, it's a procedural material, so that shouldn't be too hard. I suppose what would be best is for us to do several different 'styles' of asteroid and mix and match them

960 Polys shouldn't be
too bad as long as there are not too many on screen, but I kept to 250 because I plan to have some quite thick asteroid fields.
It's a single 1024 map for the main LOD, and it's DDS for memory saving. I'll throw some LODS on it, and re-render the textures up a bit better and make an asteroid available for dload tonight

Also, it should be noted that most asteroid ARE smooth. Call up Phobos and Deimos, the captured Mars 'moons'. They are the closest asteroids to Earth, and are pretty big, so there are good images of them. You'll see that they are pretty much smooth with a few fresh craters. If asteroids are cratered, they tend to be cratered only on one side, the side facing away from the Sun, since it is hit by small particles of matter being drawn in by the Sun's gravity.