  We survey techniques to compute the action of the Hecke operators on the
cohomology of arithmetic groups. These techniques can be seen as
generalizations in different directions of the classical modular symbol
algorithm, due to Manin and Ash-Rudolph. Most of the work is contained in
papers of the author and the author with Mark McConnell. Some results are
unpublished work of Mark McConnell and Robert MacPherson.
