I found magazine design really interesting. It isn't like book design or poster design. It is a mixture of a lot of different design. I stumbled across Inspiration Hut and found some really cool magazine designs. I also found some really cool ones on Neat Designs probably my favorite examples. Another site called Designer Daily was a great place to browse through magazine designs.
I really like the way they separate columns and lay out their pages. The clean and finished feeling that they have is inspiring.