A thought--
I always thought it was a mistake to exclude Nader in the 2000 debates. The reason? He would have taken far more shots at Bush than at Gore, and Nader in the middle would have made Gore look quite presidential. I don't think it would have hurt Gore more than Nader ended up hurting him anyway.
So- in 2004-
What if we insisted that the #1 polling 3rd party candidate was in the debate. Why?
If its a Green, again, they will take all their shots at Bush.
If its a Libertarian, what better way to deplete some of the R base?