Political Thought
http://diglib.library.vanderbilt.edu/polsci.pl?searchtext=PoPoliticalThought&Type=Simple&Resource=DB&Website=POLITICAL
From the Jean and Alexander Heard Library of Vanderbilt University, a collection of links to websites on Political Thought. Categories of the links include Modern Political Philosophers, Conservative Thought, and Liberal Thought. 

Marxists Internet Archive
http://www.marxists.org/
An archive of Marxist writings from the past 200 years. Publications include essays, letters, biographies, and more. The archives is searchable by author or browsable by subject. These publications are in the public domain. 

The Federalist Papers 
http://thomas.loc.gov/home/histdox/fedpapers.html
Essays by Alexander Hamilton, James Madison, and John Jay written to bolster support for ratification of the Constitution. 

Regarding Politics: Essays on Political Theory, Stability, and Change
http://ark.cdlib.org/ark:/13030/ft0k40037v/
From the distinguished resesarch professor Harry Eckstein, an online version of his collection of essays on Political Thought. Essays include "A Culturalist Theory of Political Change", "Case Study and Theory in Political Science", and "Civic Inclusion and Its Discontents".