The Green Party is downright scary. At best it's socialist, at worst it's on the fringes of communistic.
Consider the current paragraph from their platform (available online at
http://www.gp.org/platform/2000/index.html). See Article II Section C number 7:
7. The accumulation of individual wealth in the U.S. has reached grossly unbalanced proportions. It is clear that we cannot rely on the rich to regulate their profit-making excesses for the good of society through “trickle-down economics”. We must take aggressive steps to restore a FAIR DISTRIBUTION OF INCOME. We support tax incentives for businesses that apply fair employee wage distributions standards, and income tax policies that restrict the accumulation of excessive individual wealth.
Their underlying ideology is that for the good of society, everyone should make a decent living but there should be no big gap between the rich and the poor. They propose to cap wages and put in place legislation where those who bust their ass, grow mega-successful corporations, or have that one killer idea for an invention or something would no longer be able to become mega-rich. There would be no more Bill Gates, Howard Hughes, J. Paul Getty, John Rockefeller, etc.
This goes against the basic ideas of free market, free enterprise and capitlism. There are no more individuals, only what is good for the group. I believe this was tried in Russia for most of the last century.