One of the late 3.5 era books that I think was one of the best books of the entire era was Fiendish Codex I: Hordes of the Abyss. Not only have demons in D&D always been one of my favorite foes--rich in variety, malevolence, variety and atmosphere--but the book also managed to quite nicely balance two needs in tone: it needed to feel like classic Judeo-Christian demonology folklore, and it needed to feel like classic Lovecraftian alien, cosmic horror. And the book managed to straddle both of those tones perfectly. It's the perfect hybrid and synthesis of the two memes.
But not only are the Black Scrolls magic items of forbidden knowledge, but the back-story is eerily similar to that of Lovecraft's book. The "Mad Arab" Abdul Alhazred is not so dissimilar to the ancient scholar Tulket nor Ahm, and the fact that both have names of exotic Orientalism is, no doubt, not a coincidence. There are even allusions to a similar fate: Alhazred's: "Of his final death or disappearance (738 A.D.) many terrible and conflicting things are told. He is said by Ebn Khallikan (12th cent. biographer) to have been seized by an invisible monster in broad daylight and devoured horribly before a large number of fright-frozen witnesses." Tulket nor Ahm was apparently also killed by some kind of demonic hit squad, which not only destroyed him, but the majority of whatever country he was living in at the time.
As you can probably tell from the tagline in my blog ("D&D rules, Call of Cthulhu paradigm") anything that brings overt Lovecraftianisms to my game is to be welcomed.
As for magic items that I acutally like to use with my characters? I tend to prefer straightforward pluses to attack, damage or armor class.