I am not a member of any, but I have been seriously considering joining.

One piece of feedback that I heard, both good and bad, is that the articles that you see in their journals preceed what you see in industry by 10-15 years on average. This is great because it lets you think about these ideas in advance, and often the concepts can be useful to you. It is horrible because you won't be able to use it directly for years and years.

There are other benefits. I am undecided at the moment. What I was told by an off and on member is that it is a valuable thing to do, and he encouraged me to at least think about it (this would come out of my pocket) but admitted that his membership is currently lapsed.

(I am interested in other opinions as well...)