I like Manson, though he's more goth rock rather than shock rock, IMO. I like a few songs by Slipknot, and they pretty much are shock rock, but nowhere near anything I would call a favorite. Alice Cooper is text book shock rock, and his work from the 1970's is genius, purely classic.
G.G. Allin was basically punk, but he did have a definite shock rock aspect, especially in the style of his performance (he is right up there with Alice Cooper for me, actually). One might consider Cradle Of Filth shock rock, but that might be a bit of a stretch.
As for music that sounds shocking, I'll go with Frank Zappa. He doesn't have blasphemous/disturbing lyrics, horrific theatrics, or any of that bullshit, but when you listen to his music, it is nothing less than shocking. Especially when you consider the fact that the man never consumed any drugs or alcohol when composing his music.