Geometric Algebra

Clifford - A Maple package for computations in Clifford algebras of an arbitrary bilinear form. Includes documentations of new features and installation information, as well as downloads of the software.
http://math.tntech.edu/rafal/cliff5/

ICCA7 - 7th International conference on Clifford Analysis and their applications in Mathematical Physics. Université Paul Sabatier, Toulouse, France; 19--29 May 2005.
http://www.icca7.ups-tlse.fr/indexusa.html

Geometric Algebra and its Applications in Mathematical Physics - C.J.L. Doran's thesis on applications of Clifford algebras. Downloadable in PostScript format.
http://www.mrao.cam.ac.uk/~clifford/publications/abstracts/chris_thesis.html

International Clifford Algebra Society - Includes an abstracts mailing list, information on events and back copies of the journal "Advances in Applied Clifford Algebras".
http://clifford.org/

GA-Net - Free electronic newsletter on Clifford algebra and geometric algebra. Archive, free subscription functions and submission information.
http://sinai.mech.fukui-u.ac.jp/GA-Net/

Geometric Calculus Research and Development - Includes a brief introduction, articles and book chapters on the subject, as well as references to further information.
http://modelingnts.la.asu.edu/GC_R&D.html

Maths for (Games) Programmers: Multivector Methods - An introduction on this formalism and its applications in space-time.
http://www.iancgbell.clara.net/maths/geoalg.htm

The CLU Project - Aims to produce tools for use with Clifford algebra. Includes information on the visualisation libraries and calculators produced, as well as downloads.
http://www.perwass.de/CLU/