Most of these publications offer lots of information at a price that can't be beat. My REAL favorite, Interactivity, isn't around anymore, apparently because it couldn't sell enough ad space.
Ad space is, of course, the name of the game.
Lots and lots of ads are the reason why you get the publication for free. Visit the website and if you like what you see, sign up online for a subscription. Your mailbox will never be empty again.