I print one of these sheets, slip it in a sheet protector and hang it by the classroom door. The kids put a clothespin on their name when they leave to go to the restroom, retrieve the lunch crate etc. I can quickly see who is out of the room and also grab it on my way out for a fire drill. This makes it very easy to see how many kids I should have and who I may be missing. It is also quick and easy to update when students move in or out of my class.
Our youngest students sometimes need reminders about their dismissal plan. Simply print this out and keep it on a clipboard or near the classroom door for quick reference. If your school has an after school program, there is also room to note which kids are attending on various days.