I too am at the mercy of the snackmonster within... or at least I let myself. I have the discipline of an unruly toddler when I crave a snack. But I have found ways of working around the more insidious cravings... most times.
I switched from my favourite Haagen Daz ice cream to frozen yogurt. Say "no no" to chips, and "yes yes" to low fat multigrain crackers. Only dole out one serving of the snack (oh, this is a toughy -- I am deeply disappointed at how small a 1/2 cup of fro-yo is. It can make me cry). And I force myself to drink a glass of water before succumbing to a craving snack.
I also try not to get bored. Luckily the weather is beautiful out so I can go on a bike ride any time I like. It's harder in the winter when the snow and ice depresses me. (And before anyone kindly suggests ice skating, or skiing, or walk in the snow -- ick.)
Cookies are my downfall every time. But my new rule (and it's worked for months) is I only eat home made cookies I baked myself. I never get around to baking, so it's working terribly well!