I recently got a membership to NAPP and absolutely love it!! I got the magazine and it is the best one I know of. So far I have three of the DVDs produced by them and they are also really helpful. I think the best thing about it is getting all of the online tutorials that walk you though the steps and point out the quick keys and some techniques that I doubt I would have ever figured out on my own. Check it out here:
I also recently got a subscription to Xtrain but have not really been too impressed. The tutorials are not as useful for me but I could definitely see them being helpful for beginning photographers and photoshop users.
Photo credits: Sandra Dragojlovic.