On page http://www.math.tntech.edu/rafal/ I have recently added a link to a Maple V Rel. 5.1 worksheet with "Bigebra" package ver. 0.01 (beta). This package requires two other packages "Cliff4" and "Cli4plus" (for computations with Clifford algebras) also available for downloading from the same page.
"Bigebra" package is a result of joint work between Bertfried Fauser, Universitat Konstanz, http://kaluza.physik.uni-konstanz.de/~fauser/ and myself.
The package consisting of 32 procedures and two patches for `define/skeleton` and
`define/multilinear` is still under development and expansion. More information on the
package will be posted on the web page.