APV

To be fair, I thought I'd add the Association of Professional Videomakers to the list of video societies. All of these organisations offer benefits to members. There is another, which I don't know much about and I think is called SIVP. I think if there are any members of the SIVP on the DV forum, they will let us know before long.
Membership of any organisation has its advantages, just like the DV doctor. There is always a helping hand when you're stuck (usually instantly with DV doctor), video, sound and lighting advice from the experts, kit bought and sold and the occasional laugh in chatter.
Due to the ever evolving world of video and wether we care to admit it or not, we all need advice from time to time.
Personally, I think the internet and in particular, DV doctor is one of the best organisations in a lot of ways, mainly the near instant response. BobC deserves a great big pat on the back for keeping it all together.
Always remember - it's better to be on the inside peeing out, than outside peeing in.