At http://math.tntech.edu/rafal/cliff6/index.html I have posted a new version 6 of CLIFFORD, Bigebra, Cliplus, GTP, and Octonion packages for Maple 6.
CLIFFORD is a package of some 120+ procedures for computations with Clifford algebras Cl(B) of an arbitrary bilinear form B. It can handle matrices with entries in a Clifford algebra; quaternions, octonions (through the supplementary package Octonion), and tensor products of Clifford algebras through the Bigebra and GTP packages.
In particular, Bigebra can handle Hopf algebras.
Package Cliplus allows one to use bases different than Grassmann basis such as, for example, the Clifford basis and the dotted wedge basis.
Compiled library files contain the code as well as extensive help pages for practically every procedure. The help pages are available from inside Maple through the Maple browser. Separate .pdf files are also posted.
CLIFFORD, Bigebra, and Cliplus is a joint project of Bertfried Fauser from Universitat Konstanz and myself.
PS Versions for Maple 7 and Maple 8 are to appear shortly.