Yeah, I don't think I made the point I meant to make. Previously, I was under the (silly) assumption that folks who were trying to brute force passwords were r

Yeah, I don't think I made the point I meant to make. Previously, I was under the (silly) assumption that folks who were trying to brute force passwords were running their own rainbow set ups, generating them as necessary based on whatever per-site hash was being used. But the fact that services exist for cracking this sort of thing implies that there are plenty of sites that aren't using salts at all, and by using a per-site salt, you are not the softest target. None of this matters if someone is trying to crack your site in particular, but sometimes you just have to be faster than the slowest gazelle in the herd.