Oh, Masks of Nyarlathotep is awesome. Damn the old ones that my group got separated and we didn't get very far in that campaign. Beyond the mountains of madness is great too. Of course never had a chance to finish that one either, but man that book is big.
I concur: Kingsport and Beyond the Mountains of Madness both have their place in the pantheon of tabletop awesomeness. :)
The Masks work great with the d20 Cthulhu rules (Gives an Indiana Jones feel to the campaign), by the way, and Arkham has been released as a (decent) dual-stat supplement by Chaosium some time ago.
Never tried cthulhu d20. What I could use is an improvement to my old 4th edition CoC book (with terrible finnish translation). Have you read 6th edition? Is there really any changes, or is it the same game in a different package? Maybe I should've posted this in the product discussion of the particular book, but what the heck.
I have 6ed and d20; don't have an earlier ed than 6th so I don't know.
I think the straight game is better in a lot of ways than the d20, but the d20 ain't bad, and I just wanted it mainly to use to pump D&D up with some mythos stuff if the urge came over me.