Hi Pierre,
Having a Facebook "Page" (capitalisation theirs) sounds like a good idea. The Page could republish photos, projects, select articles and meet-ups from the JRA site. It could help share knowledge and awareness of the junk rig outside of the JRA circle.
The only downside I can think of is that it takes someone to maintain it by posting occasionally, of course. I maintain a 4000-follower Page on Facebook for my work, and I don't think the task is too onerous. I don't know how agreeable the sailing community at large is, but the only really annoying task is occasionally moderating unpleasant comments (if you care about those). As we all unfortunately know, outside of pleasant communities like this one, the internet brings out the worst in some people. We'd probably occasionally get public comments on our photos such as "Har har junks are so slow", or "My uncle had one of these and he drowned, everyone beware".
Facebook does allow administrative responsibility for a Page to be shared amongst several people, so if the idea interests the members and committee, we could put out a call for volunteers. We'd have to decide on editorial direction, if any. I feel that the committee and many highly active members are already giving a lot of their time, so if it's to happen, this project should be done in such a way as not to burden them, and especially as not to take time away from the more important activities of experimenting with and writing about the junk rig.
Regards,
Maxime