Advanced Diver magazine has interesting articles and superb photography, and now is available as a free e-zine as well. Quest magazine has some truly superb articles (whether you're DIR or not) addressing interesting topics like decompression theory. They're well-written and again accompanied by fantastic photography. It's a quarterly, and really only affordable if you get the online version. I also enjoy Underwater Journal, another on-line publication with superb photography.
I get Scuba Diving, Alert Diver, and Dive Training and I read them, and they have some interesting stuff, particularly about travel. I also read our local dive magazine, Northwest Dive News, because it will have information about local events and occurrences that won't show up elsewhere.