I am a believer in many short meals throughout the day. I avoid the urge to snack by eating something about every 2 hours. Some good choices are oatmeal (a brand without a lot of sugar), a kashi bar, yogurt, almonds, stuff like that. I have read in many sources that waiting until you are hungry to eat or only eating 3 meals a day is an invitation to over eating.
A protein shake that contains casein protein is a good choice because it takes longer to digest casein than whey or other protein sources. The longer it is in the stomach the longer you feel full. Just make sure to get a brand without a bunch of added sugar or artificial sweeteners (including Splenda). Foods high in fiber also keep you full longer.