The only organization I know that's dedicated to bones playing is the Rhythm Bones Society (RBS):

Membership
The RBS is a fun, educational, and scholarly non-profit group that does not take itself too seriously. They do, however, take their passion for rhythm bones seriously and welcome members of all skill levels, ages, and nationalities. Membership is currently $25/yr.
http://www.rhythmbones.com/rbsform.html

Newsletter
The quarterly RBS newsletter is a gold mine of information about rhythm bones. Non-members can get the newsletter for 'a paltry' $10/yr. The newsletter dates back to 1999. For a nominal cost you can get the entire collection.
http://www.rhythmbones.com/

Annual Bones Fest
Each year the Rhythm Bones Society holds an annual Bones Fest. The event is held each year in a different city. My first was Bones Fest VII in 2003. The location was Louisville, Kentucky—and it was a real hoot. We even had a conga-line with more than 50 bones players all clickety-clacking at the same time. In 2008, along with Spike Bones, I co-hosted Bones Fest XII in Saint Louis, Missouri—the first Bones Fest held west of the Mississippi River. You can get a glimpse of past Bones Fests at:
http://www.rhythmbones.com/bonefests.html

Forum
The Yahoo Groups 'Rhythm Bones' forum is the best online resource for inside information about bones. The forum moderator is Steve Brown, a warm friendly person who is Executive Director of the Rhythm Bones Society. We are all proud of Steve who made history as the first American to win the All-Ireland Bones Playing Championship. He went on to win two consecutive years (2003-04).
http://groups.yahoo.com/group/rhythmbones/

Bones History
The Web site displays an excellent overview of rhythm bones entitled The Bones: Ancient To Modern. This rare unpublished research paper was written by Ethnomusicologist Sue Ellen Barber in collaboration with the late American bones master, Percy Danforth.
http://www.rhythmbones.com/ancient.html