One of my favorite things is my students' KWL book (green book above). I buy these because the ones I buy use heavy duty paper, and they hold up all year, but you could make them by just folding paper in half with a piece of cardstock or construction paper for a cover. Each time we start a new unit in social studies or science we add an entry to to the K and W sections of our KWL book, and when students finish a unit they add what they have learned in the L section of their book.
I also use Lakeshore Learning's vocabulary journal for our content vocabulary. Adding vocabulary words is such a slooooow process at the beginning of the year, but I'm committed to teaching academic vocabulary using Marzano's vocabulary strategies, which require a vocabulary journal.
I will also be using data folders this year. I attempted them last year but bit off much more than I could chew. I love Amanda's approach on One Extra Degree on data folders, so I'm going to incorporate them this year.
I will be team teaching again this year, so I won't teach reading and writing, but if I were I would also have writing notebooks and reading journals for students. My writing notebooks are very simple 1-inch 3-ring binders, and most of my students usually bring those in as part of their school supplies. In the past I've always bought reader's notebooks for my students, and I loved them! I loved their durability and the tabs on top for easy navigation.
However, they are kind of expensive, so when I teach reading again I might try to make my own.