I'm currently doing stuffed potatoes for lunch (only eat one half for lunch though) but if you are trying to cut out carbs, that's not really going to work for you.
veggie sticks and dip is yummy. I made my own eggplant dip recently, was soooo good.
frittata is another great idea as someone else mentioned. just make a batch on a Sunday evening and cut it into slices to take for lunch each day.