Increasing portion size without calories

Adding veggies to pasta, macaroni and cheese, lasagna, frozen meals or rice can be a good way to eat more without adding a lot of calories. Get creative. I like to add carrots and spinach to my pasta, brocolli to anything with alfredo sauce, and other veggies over [any kind of] rice or [wild] rice to soup. Switching the kind of noodle you eat can make a difference as well. I like tofu shirtaki noodles (you wouldn't believe the difference in calories) and jerusalem artichoke spaghetti.

Another idea is to have a bowl of soup (preferably miso soup) or a bowl of salad before every meal so that you will not be as hungry. A lot of people do this with bread, especially at restaurants, but it's not very healthy.

My last idea is to load up your sandwich [on a whole wheat/whole grain bun] or burger with as much lettuce, tomato, onion, pickle or whatever you like without said sandwich or burger towering over.

Also thought I would suggest you try to hunt down these healthy products:
Vita brownies
Amy's organics
evol burritos
Dr. Praeger's burgers
veggie chips

all of which are truly amazing and taste great!