Abstract Algebra Online  
   Contains many of the definitions and theorems from the area of mathematics generally called abstract algebra. Intended for undergraduate students taking an abstract algebra class at the junior/senior level, as well as for students taking their first gradu
   http://www.math.niu.edu/~beachy/aaol/

Intro to Abstract Algebra  
   Paul Garrett's detailed and comprehensive lecture notes in abstract algebra.
   http://www.math.umn.edu/~garrett/m/intro_algebra/index.shtml

Octonions and Sedenions  
   Enter the world of 8 and 16 dimensional hypercomplex numbers and discover that the laws that we take as granted do not always hold.
   http://www.geocities.com/zerodivisor/

IDA: Algebra Interactive  
   An HTML-based book by Arjeh M. Cohen, Hans Cuypers and Hans Sterk. It focuses on an algorithmic approach to algebraic structures. Many of these tools and examples use the computer algebra package GAP. Site has samples and errata.
   http://www.win.tue.nl/~ida/

Algebraic Areas of Mathematics  
   Topics include number theory, groups and sets, commutative rings, algebraic geometry, and linear algebra.
   http://www.math.niu.edu/~rusin/known-math/index/tour_alg.html

A Catalogue of Lattices  
   By Gabriele Nebe and Neil Sloane.
   http://www.research.att.com/~njas/lattices/

Abstract Algebra  
   Lecture notes by David Wilkins, Trinity College, Dublin. Topics in Number Theory; Group Theory; Galois Theory.
   http://www.maths.tcd.ie/~dwilkins/Courses/311/

Macdonald Polynomials and the n! Conjecture  
   Manuscripts and Publications.
   http://schur.ucsd.edu/~garsia/

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.
   http://www-unix.mcs.anl.gov/~mccune/papers/robbins/

Center for Commutative Algebra  
   A site for the commutative algebra community, including news, conference and preprint announcements, and a huge list of algebraists.
   http://www.commalg.org/

Algebra Links  
   From Spartanburg County School District Two.
   http://www.spartanburg2.k12.sc.us/links/algebra.htm

Dave's Short Course on Complex Numbers  
   An introduction with math and a little history intended for those having a familiarity with ordinary real numbers and algebra.
   http://www.clarku.edu/~djoyce/complex/

Homogeneous Transformation Matrices  
   Explicit n-dimensional homogeneous matrices for projection, dilation, reflection, shear, strain, rotation and other familiar transformations.
   http://www.silcom.com/~barnowl/HTransf.htm

Algebra Universalis List of Researchers  
   Compiled by G. Gratzer.
   http://www.maths.umanitoba.ca/homepages/au/Researchers.html

Lecture Notes in Algebra and Number Theory  
   Andrew Baker, University of Glasgow.
   http://www.maths.gla.ac.uk/~ajb/course-notes.html

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.
   http://groups.yahoo.com/group/univalg/

Cohomology of Modules over the Mod 2 Steenrod Algebra  
   Robert R. Bruner, Wayne State University. Tables in PS or GIF formats.
   http://www.math.wayne.edu/~rrb/cohom/

Catalogue of Algebraic Systems.  
   Summary of and links to online materials concerning algebraic systems: semigroups, groups, rings, algebras, groupoids, and categories.
   http://www.math.usf.edu/~eclark/algctlg/

Math Forum: Algebra Problem of the Week  
   A weekly interactive project for algebra on the Internet. Challenging problems are posted and solutions appear on the Web.
   http://mathforum.org/algpow/

FDLIST  
   Information on representation theory of finite dimensional algebras. Papers, meetings, places, people, jobs, journals, software.
   http://www.mathematik.uni-bielefeld.de/birep/fdlist.html

Abstract and Linear Algebra  
   A forum for students on abstract algebra and linear algebra.
   http://www.math.miami.edu/forum/algebra/

Macdonald Polynomial Page  
   Includes information about the Ribbon Rule, as well as link about symmetric functions and representation theory.
   http://garsia.math.yorku.ca/MPWP/

Home Page of J. S. Milne  
   Includes preprints and course notes on Group Theory, Fields and Galois Theory, Algebraic Geometry, Algebraic Number Theory,Modular Functions and Modular Forms, Elliptic Curves, Abelian Varieties, Etale Cohomology, and Class Field Theory.
   http://www.jmilne.org/math/

All About Circuits - Boolean Algebra  
   An introduction to boolean algebra from the perspective of electronic engineering.
   http://www.allaboutcircuits.com/vol_4/chpt_7/index.html

A Web Resource in Mathematics  
   Tailored help for students in Algebra.
   http://www.mathshape.com/

VectorLand  
   An online course to get to grips with 3D vectors. Most of the material is about UK A-level difficulty.
   http://members.tripod.com/~Paul_Kirby/vector/VectorLand.html

An Introduction to the Algebraic Specification of Abstract Data Types  
   Jean Baillie, Department of Computer Science, University of Hertfordshire.
   http://homepages.feis.herts.ac.uk/~comqejb/algspec/pr.html