I am absolutely starving after working out! Even after walking. Some things that have helped me :
stay hydrated - i make sure i take at least a liter with me, and keep sipping during my activity. Lots of times I think the signal is I am hungry, when I am really just thirsty.
Have something healthy on hand - carrot chips, celery sticks, some almonds.
Plan your exercise before a meal. If you're going to be hungry after working out, then it won't be a problem if it is time to eat anyways. I usually have a half glass of juice before my morning walk, then eat breakfast when I get back and am starving.
Go log your activity, see how many calories you burned. Then see how many calories are in what you want to eat - this makes it real easy for me to choose. The workout is fresh in my mind, and I don't want to negate my effort with bad food.