Societies

AMS, Mathematics Subject Classification at the AMS 
Maths Depts Web Server 
European Mathematical Society 
London Mathematical Society 
Australian Mathematical Society 
SIAM 
IEEE 
IMACS 
GAMM

 Research Institutions

( Germany, Switzerland and Austria )

Center for Advanced European Studies and Research 
Weierstrass Institute for Applied Analysis and Stochastics 
Mathematisches Forschungsinstitut Oberwolfach 
The European Network on PDEs and Quantum Mechanics 
The Swiss Federal Institute of Technology at Zurich, Department of Mathematics 
The University of Munich and the Technical University of Munich 
University of Stuttgart with links to other mathematical sites in Germany, to the preprint server etc.

( Italy and France )

Research Centre of Applied Mathematics (CIRAM), University of Bologna (Mathematical Physics, Extended Thermodynamics, Numerical Analysis, Scaling Laws and Fractality in Continuum Mechanics) 
Centre de Mathematiques, Ecole Polytechnique, France (with links to Liste des serveurs de mathematiques en France) 
International Mathematical Summer Center (C.I.M.E.) 
Department of Mathematics, Uneversity of Trento: International Center for Mathematical Research (CIRM), Numerical Analysis 
Department of Mathematics, University of Pisa (Group of Numerical Analysis/Computational Mathematics and Links to the Institute for Computational Mathematics of C.N.R. in Pisa) 
International School for Advanced Studies in Trieste (SISSA, Functional Analysis, Mathematical Physics and others) 
National Council of Research: Instituto per le Applicazioni del Calcolo "M. Picone", Rome 
Mathematics Department, University of Rome "La Sapienza" (links to other Mathematics Research Centers in Italy) 
Centre de Mathematiques Appliquees (C.M.A.P.) and links to other French sites.

( Eastern Europe )

Links to Math Sites in the ex-USSR from Moscow University 
Mathematisches Institut, Universitat Leipzig 
S. P. Timoshenko Institute of Mechanics,Kiev 
National University of Kiev 
Institute of Mathematics, Kiev 
Keldysh Institute of Applied Mathematics 
Institute of Mathematics, Minsk 
Siberian Branch of Russian Academy of Sciences and ICT

( Rest of Continental Europe )

Department of Mathematics, Weizmann Institute of Science (links to IMU and other math. departments) 
Eidhoven University of Technology (Mathematics and Computer Science Department)

( Great Britain and Scandinavian Europe )

The Institute of Mathematics and its Application, Essex, UK 
The Durham Numerical Analysis Group with links to the Dundee Numerical Analysis server
Heriot-Watt University, Edinburg 
Center for Computational Mathematics and Mechanics (Numerical Analysis), Royal Institute of Technology (KTH), Sweden 
Swedish University Links 
Department of Informatics, University of Oslo (Mathematical Modelling Group) 
Department of Mathematical Sciences, Norwegian University of Science and Technology (NTNU), Trondheim (Preprints on Conservation Laws) 
Department of Mathematics, University of Aarhus, Denmark (Mathematical Research Centre, Mathematical Physics and PDE Group) 
Technical University of Denmark 
Semiconductor Research and Nanodevice Modelling at Leeds 
Danish Center for Applied Mathematics and Mechanics

( United States )

US Universities by State 
Institute for Mathematics and its Applications, University of Minnesota, Minneapolis 
Mathematics Department, University of California at Berkeley 
Department of Applied Mathematics, University of Washington 
Mathematical Sciences Research Institute, Berkeley 
Texas Institute for Computational and Applied Mathematics (Centers for Numerical Analysis, Nonlinear Dynamics)

( Canada )

Institute of Applied Mathematics at the University of British Columbia 
Department of Mathematics, University of Toronto, and the Fields Institute for Research in Mathematical Sciences 
The Centre for Nonlinear Dynamics (McGill) 
Association of Universities of Canada

( Asia - Pacific )

Stanford Guide to Japanese Universities and Databases

 Mathematical and Engineering Software

Software, Preprints etc from the Web 
The NAG Library 
The NIST Math, Stats, and Computational Sciences 
Diffpack and also Sintef 
Femlab 
Cyberlogic and Wave software 
Software for Education and Science 
Numerik in Karslruhe 
German Scientific Computing 
Mathematical Software (including wavelet resources) 
Pov-Ray 3D Graphics