A very interesting version of quantum mechanics. See http://www.npl.washington.edu/npl/int_rep/tiqm/TI_toc.html (and ignore the silly WhyClublet discussion on this - theologians make notoriously wishful physicists).
See also http://www.npl.washington.edu/npl/int_rep/tiqm/TI_toc.html which is a letter writen by Professor Cramer discussing objections to his ideas.
A quick search reveals a link to CliffordAlgebra.