Here are some great articles:
http://www.askdrsears.com/html/3/T030800.asp "Feeding Toddlers: 17 Tips for Pleasing the Picky Eater" It has good ideas for introducing new, healthy foods to kids.
http://www.askdrsears.com/html/4/T040200.asp "ABC's of Teaching Nutrition to Kids" I thought this one was especially good because it teaches parents how to make learning about healthy food fun for kids. It talks about how to educate kids so that they make healthy choices on their own later on and so they know which kinds of food are healthy and why. The only thing I didn't agree with was that he suggested rewards, but everything else was pretty good advice. The article talks about referring to "grow" foods for kids.
The food that you mentioned she eats has very little nutrition. As I'm sure you know, her growing body need nutrients and vitamins to grow and develop properly. She needs to be eating fruits and vegetables in her diet. I know that is easier said than done though. However, you are in control over what kinds of food comes into your home. If another hot dog or chicken nugget never enters the door, then she will have to choose something else to eat.
Your taste buds change according to what you eat. If you only eat highly processed, low-nutrient food, like she does, then that is what you will crave. If you eliminate or cut back on those foods and eat mostly whole, natural food like fresh fruit, whole grains, fresh vegetables, etc, then that is what she will begin to like. I have tried this myself and trust me, it works. A great book to read is "If It's Not Food, Don't Eat It" by Kelly Hayford, C.N.C. It's really entertaining and is cheap on Amazon.com.
Remember, if the unhealthy food never enters your home, she won't be able to eat it. It can take up to 12 times of introducing a new food before someone gets used to it, so don't give up on offering healthier choices too soon. Most parents with picky eaters find this strategy helpful: offer her what YOU and your husband are eating for dinner, if she doesn't eat it, then she doesn't have too. But, next time she is hungry, that same meal is what she is to be offered again--whether it's an hour or two later, when she decides she is hungry, she gets her same lunch or dinner that was offered the first time--there are no alternatives or snacks (unless it's the next morning, then you wouldn't serve last night's dinner for breakfast). If she knows that pb&j, chicken nuggets and hot dogs are always an alternative, then she will never try something new. I work with children at a child development center and at meal times, they never ask for an alternative because they know there isn't one. They eat what they are given.
Sorry this isn't advice on new food suggestions for lunch, but I just thought I would give a bit of advice on the possible underlying issue as well. Hope this helps a little (those articles and book are great, I hope you try them)!