MathNet/MPRESS  
   Mathematics preprint search engine. Includes some European servers not covered elsewhere.
   http://mathnet.preprints.org/

MathSearch  
   Searches a collection of mathematical and statistical preprint servers and databases.
   http://www.maths.usyd.edu.au:8000/MathSearch.html

Bibliographies on Mathematics  
   Search enabled database of citations for a large selection of mathematical specialties. Authors may add bibliographic lists or contextual references to their work.
   http://liinwww.ira.uka.de/bibliography/Math/index.html

Project Euclid  
   Full text access to the journal Annals of Mathematics; a limited number of other journals available through paid subscriptions to Project Euclid.
   http://projecteuclid.org/

EULER  
   EUropean Libraries and Electronic Resources in mathematical sciences. Searches books, preprints, proceedings, serials, technical reports, theses, and web-pages.
   http://euler.lub.lu.se/euler/engine/engine.html

Search sci.math.research  
   Search interface to access this newsgroup's archive.
   http://mathforum.org/discussions/epi-search/sci.math.research.html

Hypertext Bibliography Project  
   Search enabled database of citations for a large selection of computer science specialties. Authors may add bibliographic lists or contextual references to their work.
   http://liinwww.ira.uka.de/bibliography/Misc/HBP/

E-print Network  
   U.S. Department of Energy's search interface. Many options for fine tuning a search.
   http://eprints.osti.gov/

Citebase Search  
   Experimental demonstration of the Open Citation Project. Search citations by paper or author.
   http://citebase.eprints.org/cgi-bin/search

My OAI  
   A full-featured search engine for most of the major E-print/preprint servers. Easy to use advanced search features. Use it as a guest, or create a free account where search preferences can be saved.
   http://www.myoai.com/

SAIL-eprints  
   E-Print search engine. Includes some archives not indexed by other engines (see the "Data Providers" pull-down menu). Use as a guest or register and receive free targeted alerts and other personalized features.
   http://eprints.bo.cnr.it/

Directory of Open Access Journals  
   Covers many free full-text mathematics and scientific journals (most are peer reviewed).
   http://www.doaj.org/

AMS Directory of Mathematics e-Print Servers  
   American Mathematical Society's directory of preprint and e-print servers.
   http://www.ams.org/global-preprints/

CiteSeer.ist  
   E-print database of mathematics and science papers with citation information. Papers may be added by specifying the URL where their files reside.
   http://citeseer.ist.psu.edu/

Front for the LANL ArXiv  
   Easiest search access to papers posted on the preeminent Los Alamos National Lab (LANL) Physics and Mathematics preprint server (arXiv).
   http://front.math.ucdavis.edu/