You could encourage people to post on this list with ideas that they
want to talk about.
a way to organise that is in the wiki of the meetings,
http://puredata.info/community/organization/pd-berlin/pd-berlin-users-group/.
that's a better place for that, as there is no list dialog on this group -
most of them are beginners, and to my knowledge aren't very active in the
list.