Number magnets to keep track of kids you allow to leave the room. Use a cookie sheet with glass stones glued to scrapbook paper and a magnet. then trim in fun duct tape! (The cookie sheet magnet board is pretty sweet for multiple different crafts.
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.