Photo District News, or PDN for short. Been around since the 70's, now is a very slick and large journal for pros, with a great look at how things are done in the biz, and major issues confronting pros.
I learn something from every issue, because I'm a retoucher, but it keeps me in touch with the people making images.

Nice online presence, all open to subscribers.

http://www.pdnonline.com/pdn/index.jsp