Utilitarianism:

Bentham Project

Utilitarian Resources

Liberal Egalitarianism:

Boston Review: New Democracy Forum

Basic Income European Network

Libertarianism:

The Freeman: Ideas on Liberty

Critiques of Libertarianism 

Marxism:

Marxists Internet Archive

Marx and Engels Internet Archive

Communitarianism:

The Responsive Community ArchivesCommunitarianism

Citizenship Theory:

Civic Practices Network

Civitas International

Multiculturalism

Feminism