Nothing! The answer is nothing.
Especially if you have one of those new machines that sings to you and does all kinds of funny things that you can watch through the front window.
The truth was that we were waiting to see if the load would unbalance after attempting to level the machine, but it was oddly memorizing to watch. I think it managed to capture our attention for a good 20 minutes or so. I hope that says more about the washing machine than it does about us...