World Religions - a brief overview (This is a starting point. it is not comprehensive)
World Scripture - Harmony of World Religious Belief.
A Composite of the Gospels
The Five Gospel's in Parallel
A Scholar's Harmony of the Gospels
The Gnostic Society Library
For those interested in books of scripture that were considered legitimate by 1st century Christians, but rejected by the Roman Government take-over and formalization of Christianity, you can access these once accepted, government rejected texts here.
The "Scholars' Translation" of the Gospel of Thomas
by Stephen Patterson and Marvin Meyer