Fajitas! I saute up some chicken, peppers, onions, etc... pop it in a tupperware container, put a couple flour tortillas in foil or a baggy, and run out the door.
Sometimes I roast a whole chicken (slather on EVOO and herbs, place on top of onions/celery/potatos, 400F until it's done) and divide it up for lunches.
Basically, any dinner meal that results in leftovers is a win. Even pasta is great but a bit carb-heavy sometimes.