Barry Malzberg is a great science fiction writer. I've been reading Dwellers of the Deep, about a science fiction fan who is periodically abducted from earth, so that the aliens can try to persuade him to give him a copy of one of the magazines he collects. The dark atmosphere of helplessness is palpable, and it has the hallmark delirious rush of words I associate with his work. A nice quotation which gives a flavour of his work is this one:
Most of contemporary existence [...] is indeed a bad working draft of reality.
He really ought to be better known. Unfortunately, I think most of his 75 novels (he was very prolific in the seventies) and short story collections are out of print, though the better known ones crop up in second hand book shops quite a bit.