: In the _Letters_ Tolkien speaks of Sauron as the last being in which evil was incarnated, had a focus for the rest of us to be tempted by or to resist. He implies that there will be no more dark lords, except the "mini-dark-lords" each of us can make of ourselves, due to our fallen natures.
: So, who is this next Dark Lord you refer to, and what is MEO?

MEO stands for Middle-Earth online, and the next Dark Lord is not really incarnate in the sense of Sauron.