Contains a bunch of lovecraft's works(including poems and essays), I believe it's more extensive than what found of temple of dagon site.
Also, I have recently started reading R.E.Howard works as well, so far I read through all "The Hyborean Age" which describes the events that lead to world seen in Conan adventures, and will read further Conan stories.
What I like about these two guys is the fact you don't have any politically correct apologetics and races (espcially with R.E.H.) rise and fall according to their will to understand the world and strive for a better civilaztion, as well as warning of the decadence which awaits to the vain and greedy: when you become too sure of yourself, and oblivous to the facts and to processes nature undertake that brought you about to begin with, in other words what happens if you ignore reality.
Personally when it comes to metal, I don't think any band managed to create a fitting soundtrack or a unique "sound" which illustrates the magnitude of the macabre and adventure found in the efforts of both writers, though I believe Morbid Angel came the closest to that (to the more Lovecraftian side of things). I'm thinking following and expanding on the themes of both writers can bring about more vigor and content back to metal, should be a really interesting direction to follow.
Ahh yes, when it comes to Lovecraft I suggest to read Azathoth, 3 paragraphs of a story that contain an entire mystical grandure.
EDIT: there is a wealth of stories to be found of Robert Howard in the Gutenberg Project:http://gutenberg.net.au/plusfifty-a-m.html
(Scroll down to 'H' to find Howard)