Thornir Alekeg
Albatross!
One other thing that I do to help is to have a few fully prepared encounters that can be dropped into just about any situation. This way if the players decide to do something completely out there from what I might expect, I can drop in one or two of these and entertain the group for the day. After the session I can start preparing something that will work with what they chose to do. Often times, I somehow try to work in the dropped-in encounters so they seem like they were more significant than they were planned to be and I look smarter than I really am (not too hard, I know).