Quick Reference:

• American Mathematical Society (AMS):
  
  • AMS Home Page
  • AMS Mathematics Calendar
  • Mathematics Subject Classification (2010) [both browse and keyword lookup]
  • Mathematical items sorted by MSC Classification
    
  • MR Lookup
  • MRef Add links to MathSciNet in your bibliography.
• European Mathematical Information Service supported by European Mathematical Society (EMS)
• Library: including MathSci ,   Zentralblatt,   Electronic Journals.
  
• Google Scholar
• Preprint Archives
• Other Mathematics Information Servers   Math.Dept. Web Servers
  
• Awards and Prizes in Mathematics ([UIUC]
• NSF: Mathematical Sciences and NSF Home Page
  
• Finding the address of a mathematician.
  
• TeX
  
• AMS Index of Mathematical Software
• Hilbert's Problems

Sources of Mathematics Information

Look Here First

• The American Mathematical Society AMS Home Page, probably the best starting point for finding mathematical resources.
• EMS European Mathematical Information Service
• Google Scholar:

Preprint Archives

• Front End for the Los Alamos xxx Archive
• US Dept of Energy OSTI's E-print server: Home,   Individuals,   Groups

Gateways to Mathematics on the Internet

• V. Arnold problems and Interview
• Math on the Web (AMS)
• mathtube (Pacific Institute for the Mathematical Sciences)
• DML: Digital Mathematics Library
• Major E-journal Providers
• Some Mathematics Textbooks Freely Available On the Web
• Electronic Books
• Virtual Mathematics Museum Superb graphics.
• EINet Galaxy mathematics node
• Florida State University's WWW Virtual Library: Mathematics
• Math Archives Teaching beyond high school.
• Math Forum
• Science Resources
• Yahoo Mathematics Section

Organizations of Interest to Mathematicians

• AIP, The American Institute of Physics
• AMS, The American Mathematical Society.
• CIRM , Mathematics and Mathematicians in France.
• Los Alamos National Laboratory CNLS, Center for Nonlinear Studies.
• DIMACS, The Center for Discrete Mathematics and Theoretical Computer Science
• EMS, European Mathematical Society
• Fields Inst The Fields Institute for Research in Mathematical Sciences (Toronto)
• IAS, The Institute for Advanced Study (Princeton).
• ICTP, The Abdus Salam International Centre for Theoretical Physics (Trieste, Italy)
• IHES Institut des Hautes Etudes Scientifiques (Bures-sur-Yvette, France)
• IMA The Institute for Mathematics and its Applications (Minneapolis).
• , International Mathematical Union.
• MAA, Mathematical Association of America
• Mathematisches Forschungsinstitut Oberwolfach
• Max-Planck-Institut-fur Mathematik (Bonn)
• MSRI, Mathematical Sciences Research Institute (Berkeley).
• The National Academy of Science (USA)
• NSF WWW Home Page, the National Science Foundation.
• Newton Inst Isaac Newton Institute for Mathematical Sciences
• ESI Erwin Schrodinger International Institute for Mathematical Physics (Vienna)
• SIAM The Society for Industrial & Applied Mathematics.
• Steklov Mathematical Institute

Mathematics Departments with Special Resources

• Karlsruhe, home of Zentralblatt.
• University of Florida (last updated 1997) Bibliographies on harmonic maps and for the Journal of Differential Geometry
• U. Mass GANG, the University of Massachusetts Center for Geometry, Analysis, Numerics, and Graphics.
• Geometry Center, Includes interesting interactive graphics.
• General

Directory of Mathematics Departments

• Other Mathematics Information Servers (Probably the most complete international list, from Penn. State.)
• Directory of Institutions in the Mathematical Sciences (primarily North America)