I think the very first thing to be featured on the site is photography basics..some people are under the impression that if you click, point and shoot - then you're a photographer. However, I believe it would be beneficial to users that you discuss what apeture, shutter speed, AF,Depth of field etc is. In addition, add articles like this website (http://www.betterphoto.com/article.asp?id=26)
that shows the importance of learning the concepts with examples to match. This will produce more beautiful pictures and help them create beautiful effective pictures.

2) I think also, that you should hold competitions, once a month that anyone can enter and thus you will generate more interaction with your users and increase usability of the site....you can have macro, night, landscape, people, etc. Have a couple of judges and the rewards can be simply be being featured on the photoblog website or getting more space or if you have a newsletter, being featured. If you don't have a newsletter.... I would recommend you get one.

3) Tips and tricks is all about working with photoshop and there are millions of links out there for example pslover.com that shows you how create an image of epic beauty.

4) Camera reviews and comparisons

5) Another suggestion is, critque and review of other members photos from both you and the members of the photoblog...that is, if they wanted constructive critique

6) If you want even more ideas - I would suggest using the Digital Magazine or any Photography Magazine out there as it has numerous articles on how to do this such as fast action photos, macros, night photography etc...