read-only groups or membership lists
It would be useful if we could have more control on members in groups (or even lists). Without it, we are forced to restrict such access through RSS to external, closed sites, which is not always ideal. I am specifically suggesting the following:
a) invite people to non-public groups and only give them view access
b) configurable option to control whether the members can see who else is a member of the group, and even the total number of members.
c) allow selected individuals to post into a group that is otherwise read-only for others (and all new members).
d) optionally specify if the posting user should be the author of new posts, or if new entries should be posted "by the group" (no user information).
e) following the above; this would also mean that it would be very nice to be able to moderate/quality-control new posts before they are made available to the non-moderators of such groups. This could spur more interest from business-like groups, perhaps a feature worth paying for.
f) sometimes it is the case that such groups could be lists, with no need for group features, so also lists should offer this possibility, but right now lists are only public or personal/private. It would be interesting if lists could have memberships too.