As mentioned, use your grocery store's prepared foods. I like to supplement with fresh fruits & vegetables. Cut stuff up and put them in portion containers when you buy them, so you can just grab and go as necessary. Pick up a rotisserie chicken every couple of weeks - that thing is good for many a meal and is so easy to just slice up or use with other ingredients. Inexpensive too!

If you're into healthy, pick up some kashi bars or similar (watch the carbs and calories on the energy bars, many of them are not particularly healthy as just a snack) to have on hand with other easy to grab snacks (dried apple snacks from costco is a personal favorite at the moment).