www.concertina.net
primarily a discussion and contact forum owned by Paul Schwartz and sponsored by a number of concertina enterprises
There is a lot of information there also but somewhat unstructured and the search monitor is not very easy to use in my opinion.
.yes I agree,I also find the adds rather irritating,but even more annoying is the large donate sign.
however, concertina.net website is better designed than www.session.org,on concertina.net it is possible to edit posts, delete posts,and bring old posts back up to the top.