Personally, I think a good moderator is someone who relates to the community and who puts a good effort into what they do.
I don't think we can really say that a good mod should be able to spell, or must be sweet and fluffy, (although these are great bonuses =)... but as long as the mod tries and does their job, that's a good foundation to a good moderator.
Participation, communication, and mutual respect is key I think.
Alas, we're having a discussion as to what we think is important in a moderator as we are doing some changes on EO to help improve the community. We want to know what you all think is necessary in choosing our moderators.