I happened across an entry for the Cthulhu Mythos on Wikipedia today. I was surprised to see that it had a really comprehensive listing of all the gods, creatures, and such in the mythos.
The entry also did a good job at bashing August Derleth, hehe.
I added the Temple of Dagon to the list of references
I am often suprised with the depth of entries at the Wikipedia sometimes. I find it interesting that it is able to often be a good resource. One would think that such an 'open' method would lead to much chaos