Making too much food and saving it is the best. Just increase the recipe and save an extra portion or two. If you don't want to just eat exactly the same thing you had for dinner, you can do things like roast a chicken for dinner and then shred the leftovers and make burritos for work (freeze them wrapped in foil). You can also make big batches of hearty soups and stews and freeze them to bring to work.
I am too lazy to make food before I leave, so if I have to make a lunch (instead of just grab leftovers), it is not going to happen. Instead, I will buy bread/lunchmeat/greens/cheese and keep it in one of the fridges we have in the office along with some mayo/mustard. It's not an option for everyone, but it works for me when I get tired of the nearby lunch places.
The only real food store that is a short walk from my office is Target, so I end up with the hillshire farms (or target brand) deli meat. It's not bad, and it comes in little tupperware containers that are great for freezing single servings of soup....need to go make some soup soon...anyone have any good soup recipes?