How about the same color assigned to each person? Especially the poster him or herself? And it could certainly be random. Just, consistent to each person. Y'know?
With that as well too, the option in setting for choosing your own color, or maybe even the first few colors for people who reply to you, and after that it's random.
Personal and random colours might be cool but the only reason I say might is that once all mixed together chances are it won't be aesthetically pleasing. Could be a mess of colours.
I agree, and I think a good start is that your color is the same for you, and other people who post have the same color for them. That the colors go per user, not post/reply.
