arXiv.org e-Print archive
Science, Publications, Archives, Free Access Online Archives - ArXiv.org. An Open Archives Initiative (OAI) compliant archive of electronic preprints in physics, mathematics, computer science, and non-linear sciences.
http://arxiv.org/
Organic Eprints -
Science, Publications, Archives, Free Access Online Archives - Organic Eprints. Open access archive for papers related to research in organic agriculture.
https://orgprints.org/
CiteSeer
CiteSeer: Scientific Literature Digital Library incorporating autonomous citation indexing, awareness and tracking, citation context, related document retrieval, similar document identification, citation graph analysis, and query-sensitive document summaries. Advantages in terms of availability, coverage, timeliness, and efficiency. Lee Giles, Steve Lawrence, Kurt Bollacker, Isaac Councill.
https://citeseer.ist.psu.edu/
PhilSci Archive -
Science, Publications, Archives, Free Access Online Archives - Philsci Archive. An electronic archive for preprints in the philosophy of science.
http://philsci-archive.pitt.edu/