If you haven't already, start a reflection journal, blog, or podcast to record your memories of the school year - what lessons were effective, which might have needed more content or tweaking, and what lessons that were total disasters! Making notes in the margins of your teacher editions is a shortened version of this type of reflection.
Have your students reflect on their year by making scrapbooks of pictures you've taken, drawings, stories, stickers, and so on. Some students treasure these memories. Have students write in each other's memory books - just make sure it is something positive!
Reduce, Recycle, Reuse
Go through your desk, closet, shelves, and student desks and get rid of stuff you didn't use or won't use in the future. Most schools have a central location that teachers can leave their "used-up treasures" and others might find new uses for them! A lot of my personal furniture came from other teachers' rejects.
Be sure to recycle or reuse old worksheets that students didn't need. I always kept a couple of extra copies of worksheets for kids who might have lost theirs and for kids who were absent. This pile grew quite large by the end of the year. I sometimes donated the paper to my church for drawing paper for Sunday school students, but I usually just kept them for scrap paper for the following year. Some students even liked going through the stack and taking worksheets home for the summer in order to play school!
In my years of classroom teaching, I always gave out awards to each student - and they weren't always for scholastic ability. I did give the top student in each subject a special award, but EVERY student went home for some kind of certificate or ribbon. Categories always included, best use of school supplies (crayons, markers, kleenex, etc.), artistic and musical abilities, friendliest, most caring, most generous, storyteller, and so on. You can certainly make up your own categories that fit your students' personalities and abilities. I invited parents to the award event on the morning of the last day of school so they could share in the fun. I tried to give awards to parents when they were there, too. (You will cry on the last day of school!)
Remember Mary Kay Ash of Mary Kay Cosmetics? One of her quotes says that "Everyone has an invisible sign around their neck saying, "Make me feel important". Never forget this message when working with people." This is especially true of your co-workers, including the school custodians, cooks, teachers' aides, and volunteers at your school. Look those people in the eye and say a genuine "thank you" for what they do for you. All of the people in a school make it a better place and they deserve to feel valued for their service.
Leave your room looking better than when you found it. Attend retirement parties - those teachers have worked hard for a long time and deserve dignity and the respect of beginning teachers. Make sure you leave positive notes on students' report cards, even though it takes a long time. Be careful to never burn bridges behind you. You never know...