C'thul'hu for president!
A store chock-full of C'thuliana, from stickers to shirts to books. Fun to poke around in.
A short story written by Neil Gaiman as a dictated autobiography of C'thul'hu.
A web application that lets you randomly generate the contents of a greenbox (a hidden stash of equipment) for the tabletop RPG Delta Green. The Generator will also let you add your own items to the database.
A wiki intended for the game Delta Green by the denizens of the D-G mailing list. Contains speculation and discussion of elements of the metaplot, story ideas, additions to the game setting, adventures, and more. Much of this information is repurposable for other game settings (like GURPS, Conspiracy-X, and possibly Eclipse Phase), though anything that specifically references CoC or D20 rules will need to be rewritten.
A lorem ipsum generator that churns out Lovecraftian creature babbling and wailing. If you want to create a mythos tome, an evocation, or just random looking text to fill out some fields this will work.
A blog dedicated to C'thul'hu mythos-related props and other crafts.
The homepage of a Lovecraftian hip-hop group. Pretty good stuff - I recommend McMurdo Boogie, after At the Mountains of Madness.