Thierry Dana-Picard's question provoked two immediate replies by Peter
Webb and Martin Wursthorn which both stated: I have written GAP
routines ... . I enjoyed seeing this, I think it shows that the
GAP-forum serves its purpose.
However I would like to take this instance to appeal to use the
GAP-forum also for informally informing others of the existence of
such routines without waiting for a question. This aspect has not been
emphazised when the function of the GAP-forum was explained in the
README file with the announcement of GAP, but I think as time proceeds
there will be more such "hidden treasures" which might be useful for
others as well if one knows of them. So please tell in the GAP-forum
about routines that you have written (and hopefully are willing to
share) as well as about interesting applications. It should be clear
that since the GAP-forum is unrefereed this does in no way conflict
with formal publications.