What do moderators use to find out your indentity besides you ip address?

As far as I know most moderators that I've talked to when it comes to Yahoogroups know more about their members' IDs by looking at the membership list for their group. It could be that each group is set up differently which is why you ask about the IP address because I know some messageboards on the Net have it set up that the IP address is logged there as soon as you post.