Definately agree with Lia. When you have a kazillion students, seating charts help you remember their names (or at least give you a place to look if you can't remember their name) and help you have some positive control. Also, in a class like art where students only meet once a week, it gives that student a "home" and a place that is theirs, for that period of time each week.
I also have a color coded seating chart that I use to assign class jobs the jobs rotate each week....but is easy to manage becuase each student has a color and what ever job that color has that week is your job. It is especially effective with youngsters who cannot yet read! So if you know what color you are, you know what your job is!
Although...funny story...last year I had a special needs student who is african-american. I gave the direction that all the green people needed to help pick up the floor. This student's aide gently reminded him that he was a green person and he remarked, "No I am not a green person, I am a black person."
Of course this ranks right up there with the time some second graders got into the debate as to whether there were dinosaur bones or dragon bones burried on the playground!