We use Basecamp for project communications.
We use Basecamp for shared conversation threads, which might occasionally include an attached content item under discussion.
You can upload or download items from your basecamp project website to your computer at any time.
Generally we use it as a substitute for all communications that might otherwise go through email. This is because it is a shared environment, designed for teams of people to use. All people invited to join the Basecamp project can access as required.
Whenever a new post is created to an existing conversation thread (or a new thread is created), all members of the project will receive a notification email containing the post, along with a link back to that post on the Basecamp website.