We do the low-glycemic, whole foods thing. Lots of non-starchy veggies, big variety of legumes, some whole grains like barley and quinoa, some low fat dairy like kefir or plain yogurt, a little lean meat like fish, poultry or bison, egg whites, sprouts, nuts seeds and unsaturated oils, a little fatty fish for the omegas. End up eating lots of salads, soups and stir-fries. We rarely eat out and pack our lunch most every day.
Glory87 and BlueToBlue mentioned volumetrics. I too eventually realized that I really like to eat and hate to feel hungry. So I'm a big believer in fiber-rich foods of low caloric density that will see me through to the next meal. Then I discovered somebody had a catchy name for it!