For those thinking of running the Tatters of the King campaign for their players, take a look at these below web-sites. If you'd like to read more articles on this campaign in this blog, you can find them over here.
Tatters of the King Picture Links
This is a thread containing a number of beautiful pictures and hand outs for the Tatters of the King campaign. While most of them are book covers and therefore don't need to be printed out, they're still worth showing to your players to give them a vibe about what they've found.
Tatters of the King Wiki
This is a pretty comprehensive campaign wiki for Tatters of the King that talks about the NPCs and brief summaries about what occurred during the game. This is a really good resource, particularly if you just want to brush up on a few succinct facts in preparation for the game. I really wouldn't read it as a player, however, as it's filled with spoilers.
An interesting thread at Yog-Sothoth.com which goes into several perceptions of Hastur. While not strictly necessary for Tatters of the King, it's still an interesting read to see what other people might think. While it's an old thread, the yoggie forumites are pretty happy with digging up threads out of the graveyard so long as you add something new so feel free to post if you have anything to add.