Contains indexed bios and background information on many theorists as well as many on-line texts of important works. This site uses frames and may take a bit longer than usual to load in, but it's easily worth it. The Political Philosophy Reading Room A nice site of political theory texts available on-line, categorized and neatly presented. This is a great, searchable site dealing with classical Greek and Roman texts. If you're interested in classical political ideology, this is the place to check out.
Many texts are available in full text format and are often annotated for better understanding.
This site uses many frames and may be slower than others but it is well worth a look. An excellent searchable archive of texts by and about Karl Marx and Friedrich Engels. Anarchy Archives A collection of writings by and about anarchy and anarchists. A collection of links out of the University of Colorado at Denver on Postmodern thought. Many links can be found here on thinkers such as Baudrillard, Derrida, Foucault, Lyotard, Rorty and others.