Jordan Theory Preprint Archives
- Jordan algebras and related topics (~100 articles).
- http://www.uibk.ac.at/mathematik/loos/jordan/

Markov Chain Monte Carlo Preprint Service
- A list of all registered papers on MCMC methodology currently submitted for publication. Based at the Statistical Laboratory of the University of Cambridge.
- http://www.statslab.cam.ac.uk/~mcmc/

Shelah's Archive
- Papers by Saharon Shelah in logic and related. (100s of articles, arXiv mirrored)
- http://shelah.logic.at/

Topology Atlas Preprints
- Mostly general topology. (400+ articles)
- http://at.yorku.ca/topology/preprint.htm

Center for Commutative Algebra
- Preprint announcements and links.
- http://www.commalg.org/preprints/

Optimization Online
- A repository of eprints about optimisation and related topics.
- http://www.optimization-online.org/

Linear Algebraic Groups and Related Structures
- Including Azumaya Algebras, Algebras with Involutions, Brauer Groups, Quadratic and Hermitean Forms, Witt Rings, Lie and Jordan Algebras, Homogeneous Varieties. DVI, PS, PDF (~80 items).
- http://www.mathematik.uni-bielefeld.de/lag/

Cryptology ePrint Archive
- At the IACR.
- http://eprint.iacr.org/

Banach Space Bulletin Board
- Banach spaces/functional analysis. (~400 articles, arXiv overlay)
- http://www.math.okstate.edu/~alspach/banach/

Conservation Laws Preprint Server
- Analysis/simulation of conservative PDEs. (100+ articles)
- http://www.math.ntnu.no/conservation/

Mathematical Physics Archive
- Also called mp_arc; at UT Austin. (2000- articles)
- http://www.ma.utexas.edu/mp_arc/

K-theory Preprint Archive
- K-theory (generalized cohomology theories). (~400 articles)
- http://www.math.uiuc.edu/K-theory/

MGNet Preprints
- Multigrid and other methods for PDE simulation. (100+ articles)
- http://www.mgnet.org/mgnet-papers.html

Hopf Topology Archive
- Algebraic topology and related areas. (~400 articles)
- http://hopf.math.purdue.edu/