I quit 75 days ago and am doing splendidly. I initially gained about 7 or 8 pounds, but have since taken off 4 of those. I exercise a lot (running, biking, and some light weight lifting), but I think my body just needed to adjust to the metabolic differences. When I smoked, I often used cigarettes to fend off the nibblies, and it worked. I ate three times a day and that was it. Now, I'm a little more prone to snacking and have had to get a grip on it. I think smoking also revs the metabolism a good bit, so one is burning more calories. This adds up over the long term.
When I first quit, I was eating quite a few spearmint Lifesavers, and it helped a lot. After the first week, I didn't need them anymore. Now I try to drink at least four bottles of water a day, and my snacks are apples, celery, cucumbers, sunflower seeds, and raisins.
Some people might disagree with this tip, as it's rather like a vegetarian mashing her tofu into the shape of a turkey, but I'll give it anyway. I have a wooden dowel that is the same size as a cigarette. I keep it in my top desk drawer, and occasionally I take it out and play with it. It seems to satisfy my urge to roll something around in my fingers.
Best of luck, all. Smoke free and loving it!
I'm trying to eat right and exercise. 
