After reading that thread about the slipping and the wreck I thought about another technique.
When stopping at a toll booth, since they are so slippery even when it's not raining, due to the high volume of traffic they see stopping there, pull up as close to the window as possible, so if your foot slips, it hits the curb and you can try and brace yourself on the booth. Don't know how many people it applies too, but I have several toll roads I travel frequently, and our instructor said this was really important.