I am in a very laid back, informal 'club' if you want to call it that... Basically a bunch of homebrewing goofballs who occasionally get together and sample each others' fares, attend homebrew comps and local brewery events or have a group brewday at someone's place...
The good : getting opinions on your beers, learning other people's processes, advice on equipment / set ups, grain buys, general good times.
The bad : can be club politics to deal with, dues, snobbery, general discord...
Just go hang at a few clubs and get a feel for them...