Re: HR Giger.
Haven't gone looking, but I do recall there were at least one or two threads on Giger and his work around here someplace....
At any rate, I'd say he is simply a surrealist, albeit with a good deal more interest in technology than the classic surrealists are perhaps considered as having by most. His work has the same blurring of lines, the same mixture of dreamlike/nightmarish symbolism and eroticism, the same meeting of death, decay, and sex, and so on, that one sees in so many of the surrealist artists.
At his worst, rather confusing. At his best (which is quite often) extremely disturbing and unsettling, and very powerful.