Hey, chuck -- if you're starting to make the 'roids, I've got a great tool that can help make some of the materials (including normal maps). I don't remember the name of it off the top of my head, but it's on my desktop at home, I'll send you a link.
Also, I think there's an blender plugin/script somewhere that will make the roids for you. I seem to recall playing with it, and not being entirely disappointed. Though, I don't remember what the mesh itself looked like, with regard to it's actual construction (number of polys/tris, etc.)
EDIT: The material editor is MapZone
http://www.mapzoneeditor.com/ Takes a little getting used to, but I've liked the results. Plus, you can build a "generic" form and have it re-roll the random numbers so a different, but similar map is generated -- perfect for asteroids in the same belt.