The Social Science Research Network (SSRN; http://www.ssrn.com/ http://www.ssrn.com/) is an effective preprint service for the Social Science that seems to have

The Social Science Research Network (SSRN; http://www.ssrn.com/ http://www.ssrn.com/) is an effective preprint service for the Social Science that seems to have the same professional clout as ArXiv for it's domain. Yet there are no respective preprint services for biotechnology... why? Seems like there should be one just by connecting the dots between ArXiv and SSRN.