Nature Precedings

NPG (Nature Publishing Group) just launched its own pre-publication server. The idea might come from arXiv.org. But they occupy different fields: Nature Precedings welcome high-quality contributions from biology, medicine (except clinical trials), chemistry and the earth sciences; while arXiv service in the fields of physics, mathematics, non-linear science, computer science, and quantitative biology.

See its introduction:

Nature Precedings is a place for researchers to share documents, including presentations, posters, white papers, technical papers, supplementary findings, and manuscripts. It provides a rapid way to disseminate emerging results and new theories, solicit opinions, and record the provenance of ideas. It also makes such material easy to archive, share and cite. The whole service is free of charge.