These are a couple of information sources for those who aren't as versed in the worlds of Shin Megami Tensei.

http://www.popanime.net/megami/wiki/
A wiki for the Shin Megami Tensei series. Contains a demonic compendium that could be of great use to anyone

www.godchecker.com
A database of deitys, spirits, and other mythological beings from various mythologies. Looking for a demonic form, avatar tuners? Look here