Abstract Algebra - Lecture notes by David Wilkins, Trinity College, Dublin. Topics in Number Theory; Group Theory; Galois Theory.
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 graduate algebra course.
Algebra Links - From Spartanburg County School District Two.
Algebraic Areas of Mathematics - Topics include number theory, groups and sets, commutative rings, algebraic geometry, and linear algebra.
Center for Commutative Algebra - A site for the commutative algebra community, including news, conference and preprint announcements, and a huge list of algebraists.
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.
FDLIST - Information on representation theory of finite dimensional algebras. Papers, meetings, places, people, jobs, journals, software.
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.
Homogeneous Transformation Matrices - Explicit n-dimensional homogeneous matrices for projection, dilation, reflection, shear, strain, rotation and other familiar transformations.
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.
Intro to Abstract Algebra - Paul Garrett's detailed and comprehensive lecture notes in abstract algebra.
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.
Octonions and Sedenions - Enter the world of 8 and 16 dimensional hypercomplex numbers and discover that the laws that are taken for granted, but do not always hold true.
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.
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.
VectorLand - An online course to get to grips with 3D vectors. Most of the material is about UK A-level difficulty.