I've blogged about seating arrangements here, and you can see my seating charts here.
Here are a couple of new seating arrangements. I used this one for Speed Dating--actually Speed Meeting. (Valuable when students have to share information with a classmate. They can move quickly to change chairs and partners.)
Now, I am experimenting with this V shaped arrangement.
I like changing the desk arrangements. Different activities call for different arrangements. Upon seeing a new arrangement, students expect to be doing something different. Switching it up is good for them and for me.