OK, well, peoples' language can sometimes be an indicator. If someone is using a lot of slang, to the point that they just sound silly, I usually assume that he/she is a white person.

Sigs as well. If someone has a quote from something like Deltron in their sig, again, I assume the person's white.

But more than anything, the content of the post is the best indicator of a poster's race. Especially if they sound really defensive.

Yeah, I know this is probably wrong of me, but it's also a reflection of our messed up society.