Christianity

• Catholic
• Protestant, Orthodox & Other

Islam

• Introduction to Islam
• Islam, the Modern World, and the West: Contemporary Topics
• Centre for Islamic and Middle Eastern Law
• Islam and Human Rights
• Liberal Islam Network
• Understanding Islam
• IslamOnline.net
• IslamiCity.com
• Aljazeera.net
• Islam101

Ecumenism

• BBC World Service: Guide to Religions of the World
• A Common Word Between Us and You
• Research Guide for Christianity ( Yale Divinity School)
• Ecumenical and Interfaith Relations (Webster Univ Library & Luhr Library-Eden Theological Seminary)
• Ecumenical and Interfaith Dialogue Resources (Flora Lamson Hewlett Library, Graduate Theological Union)

Social Sciences & Religion

• Religious Movements Homepage
• Sociology of Religion (Wikipedia)
• Fundamentalism (Wikipedia)
• Adherents.com (statistics and religious geography)