You may like Rosemary Conley's cookbook/diet *Eat Yourself Slim*. After 30 years of advocating strictly only 4% fat foods, and nothing at all that's *naughty*, she realised that people who lost their way on the diet usually did for the same reason you describe. A little craving turned into a big binge. So she worked into the diet 150 cals a day treat and this can be high fat, or anything. You can save those cals up for a couple of days if you like, so you can even eat a Mars Bar and stick on the diet, so long as you figure out your calories accurately! She wrote that since making this change, even more of her dieters have succeeded in losing the weight and inches. Binges are probably the biggest diet killer, so any diet that can try and head them off at the pass is probably going to suit you better.
She also says, like someone else above, if you do have a binge, or commit an indiscretion - just carry on with the diet at the very next meal, maybe exercise a bit more that day or the next - and forget it. We're all human.
If, on the other hand, you try introducing a bit of naughtiness into your diet but really can't stop at one bag of crisps, or one bar of chockie - then she recommends you forget the treat until you feel you can handle it.
I think another thing worth remembering for us all is that if you up your exercise ever so slightly, that covers the odd indiscretion as well.
The sort of diet that won't let you drink alcohol or have a treat, or stray in a controlled manner from the basic rules, is not for you, as you need to find a diet where you can have some treats to look forward to, otherwise when you have got to target weight, it will all pile back on again the minute you relax control. In other words, a diet that allows you some freedom also is developing your ability to regulate yourself, and do self-control - a strict diet that treats you, emotionally, like a naughty child, is only a temporary fix. So if your diet won't allow you some freedoms, find another that will! That way the crisps don't become the holy grail, just an occasional treat you can have and then move on, from.
I remember seeing the BBC's Diet Trials the other year and this one woman was on a low carb diet. She lost weight OK but she fantasised constantly about eating bread and seemed pretty miserable. There are diets out there that will let you eat bread and you'll still lose the same amount of weight, so it's best to pick a diet that suits you in the first place, rather than one that will force you to sacrifice something you love! I suspect after the Trials she put the weight back on, as well.
What follows if just for if you're ready to get rid of the crisps forever.... Another technique you can learn to control cravings is outlined in Paul McKenna's *I Can Make You Thin*, book and CD. He gives you two ways of dealing with cravings - one to control them every time they arise but another really heavy duty method you should only use if you never want to eat something again. I was with my chocolate-eating neice all weekend and when we went to town, walked into a handmade chockie shop with her - 2 months ago I'd have spent a fortune and ate the lot. Now I just looked at them and thought *yuck*. So it works! I've also withstood my 5 year old's birthday party (a kitchen full of sweets and chockie, and baked cakes I haven't even felt an urge to try one) - so I can vouch that Paul McKenna's methods work.