In forum permissions, there is an item "Can View Thread Content" and it's help reads "This permission controls whether or not users can view posts within a thread. This permission is independent of whether or not users can view the actual thread links within a forum."
When we set this to No and "Can View Others' Threads" to Yes, it works - you can see other people's threads listed, but you can't see the contents. When we try the opposite though, it doesn't work - there is no way to not see other's threads listed but be able to see the contents if we get the link somehow. At least I haven't found out how to do this yet.
This is something that I would love to see - a forum where everyone can post hidden threads and see only his own threads listed, but also be able to see other user's thread contents if they send us a link to their thread. Any ideas how this could be done?