There is a great event planning blog called (of course) Brilliant Wedding Planner where I just saw this post on chair ties. I appreciate a little creative pushing when it comes to event designing since there is so much out there, it's difficult to decide what's great and what's been done a bazillion times. So here are some options.
Of course, here is your classing horizontal chair tie:
Here is the vertical idea that was recommended on Brilliant Wedding Planner
Just, whatever you do, please don't do this. ;o)