Robbins Algebras Are Boolean
A web text by William McCune describing the solution of this problem by a theorem-proving program, with input files and the proofs.
www-unix.mcs.anl.gov Details

The Math Forum
Combined archive and portal to web resources, educational issues, help forums, mailing lists, and teaching materials.
mathforum.org Details

The Mathematical Atlas
Dave Rusin's survey of research-level mathematics, with introductory articles for non-mathematicians and hyperlinked bibliographies in each of dozens of research areas.
www.math.niu.edu Details

Univalg Mailing List
Mailing list for use by the Universal Algebra community. Universal Algebra is a technical branch of mathematics related to algebra and model theory.
groups.yahoo.com Details

VectorLand
An online course to get to grips with 3D vectors. Most of the material is about UK A-level difficulty.
members.tripod.com Details