Back to school idea - "We're looking back on summer, this is what we see!" Have students draw pictures of things they have done over summer break in sunglasses. You could also do it for things students are looking forward to this year.
Back to School Survival Kit - put in a cute treat bag and pass out during Open House or have on the student's desk for the first day of school - I use to make these for my first graders - thinking about doing it for the my middle schoolers.
My teacher uses a Noise Meter similar to this one. The Noise Meter is a cool way to remind students the correct noise level that they should be using! You just use the paper clip and move it to the appropriate noise level the students should be using.
I love this idea and the fact that there are different sticky notes used! Confessions of a Teaching Junkie: The BEST First Day Ever! I may have to use this for the first day/or back to school after winter break