From the School of Mathematics and Statistics at the University of St Andrews, Scotland, collection of web pages featuring biographies, histories of math in various countries and timeframes, and other topics.
From the University of Tennessee Knoxville, links to software, teaching materials, articles on topics in mathematics, and full text of some mathematics conference proceedings.
From the Konrad-Zuse-Zentrum für Informationstechnik Berlin (ZIB), collection of mathematical resources and links to both indexes and full text publications.
From Penn State, collection of links to websites of academic departments, professional associations, commercial sites, and other sites focusing on mathematics.