i have been attempting to make volumetric rings using clouds and functions i have had a little success but as the cloud needs to be very big and most of it is not rendered as cloud it is very slow. here is the file[attachurl=#] if someone can make sense of it maybe someone can help me get color into it. i think the advantage of doing it this way over disks is that it is more corect so you get shadows under it and backlit rings where the sun shines through. if this doesn't work at least i'm learning functions!!
You might like to check out this thread we were playing in a short time back: http://forums.planetside.co.uk/index.php?topic=8989.msg96817#msg96817
I also uploaded the .tgd to this image some time ago: http://forums.planetside.co.uk/index.php?topic=9413.0
The rings are volumetric and, whatever colour you want them to be. :)