I just came across this in the New Tools Workshop Wiki and thought it would be worth sharing with everyone.
Basically the site allows you to copy your class lists into the system, which creates seating charts that can be rearranged by dragging on screen or randomized for mixing them up and printed out each time. A link is sent to you that you can use each time to modify your class. It can also generate groups of various sizes randomly so that you are saved that task, the other thing the system does is pick names from a virtual hat, which is a great way to vary the students to whom you ask questions in each class. There are plenty more goodies on the site to investigate, but I thought that these tools in particular might be very useful to some of you since it is the beginning of the year. By the way it is free and no registration is required.