There have been already two attempts to answer J. Neil's question
about possibilities of calculating in group rings of AG groups. Let me
give a third hint: Martin Wursthorn at Stuttgart (working in the group
of Prof. Klaus Roggenkamp) has a set of standalone programs written
for the investigation of modular group rings of *p-groups* (given by a
polycyclic presentation) which e.g. computes automorphism groups of
p-groups but also unit groups of such group rings. Together with
Martin Wursthorn we are planning to make this set of programs
available as a further "share library" through GAP in the not too far
future. Maybe this is of interest.

Joachim Neubueser