GlassFrog allows users to make the projects they own visible only to members of the circle that holds the project.
(Please note that members who are excluded from meetings are still counted as members of the circle and will be able to see all of the circle's private projects. They will also be able to see all private actions, etc. that are assigned in Tactical meetings, both through the Notification process and through the meeting history page.)
To make a project private to the circle, simply check the box marked with that label, for a new or existing project, and then click Save.
Note that this will have the effect of making the project private to the circle even if the GlassFrog organization has been marked as public. See more information on this premium feature here.