general
Most Dutch scoutinggroups have (at least) one stam (plural:
stammen). But there are many differences between these
stammen. They can have any given number of members, they
do not all wear the scouting-uniform and don't all meet every
week.
Members of a stam are often leaders of a younger unit as
well.
activities
Like mentioned above, stammen differ so much between
each other, that it's really difficult to name activities they
like to do. A large part of their programs usually consists just
of being together, talking about what they did since the last
time they met, and having "a few" drinks while doing
so.
In the Netherlands there are several stammen that are specialized
in certain things you sometimes need in scouting. These units
sometimes have members of different groups across the the Netherlands.
The M.E.S. (stam specialized in first-aid) and explo-stam (specialized
in outdoor activities) are examples of these type of stam.