I just created a mailing list for discussions of the ideas and social influence of the world's visionary thinkers. This list is associated with the Great Thinkers site that I maintain.
The list is free and unmoderated.
You can subscribe to it at the following URL:
http://www.onelist.com/subscribe.cgi/visionaries
Archives will be available at
http://www.onelist.com/archives.cgi/visionaries