Stanford Encyclopedia of Philosophy:
http://plato.stanford.edu/entries/aristotle-politics/index.html
Contains a lot of good, basic information about Aristotle's Political Theory and his view of politics. Also has a nice bibliography.
The Catholic Encyclopedia
http://www.newadvent.org/cathen/01713a.htm
Great resource for biographical information and an overview of Aristotle's philosophy as well as information on his school.
Philosopher's Lighthouse
http://library.thinkquest.org/18775/research/arlink.htm
A list of links to online Aristotle resources.
