Some ideas... Please keep in mind I'm a "health nut," I tend to make a lot of homemade foods, and I do allow my kids to buy a school lunch every so often...
* vary the bread or other carb/starch - Rather than slices of bread, you could use tortillas as mentioned, English muffins, pita pockets, dinner rolls, or mini sub bread or bagels. If they like sushi then go with that and make them using your child's favorite ingredient. Also, I would say crackers, but many have hydrogenated oils in them.... On this note whether we as parents are eating low carb kids need carbs for their growth, development, and especially for energy.
* dipping is popular - Whether it be fruit dip, salad dressing, or something like hummus kids like to dip their food. Dippable items include sliced fruit, veggie sticks, pita chips (make your own), etc. Dips can be stored in little plastic containers.
* noodles and sauce are good - spaghetti and long noodles, bow ties made with a white sauce and peas, mac and cheese, etc. can easily be transported in a thermos. Just add hot water to the thermos first, let sit, throw the water out (better to recycle it, though), and then add the food.
* salads can be appetizing - You can make your own kind pleasing veggie or fruit salad. For veggie salad have your child help you make it or at least know what they like or maybe start a salad tradition. Then again my kids love veggie salads. I add lettuce, cucumbers, some homemade croutons, baby tomatoes, some sliced meat or hard boiled egg if they want, and some dressing in a little container.
For fruit salad they also help me by using a butterknife to cut their fruit. Watermelon seems to be a favorite.
* Of course, leftovers are an obvious choice. Sometimes I make it more fun, such as baking a potato and using leftover chili and shredded cheese as a topping. or let them take tortilla chips and have chili in a thermos.
* supplement with healthy homemade desserts or snacks, like muffins, cookies made with applesauce, and other baked goods
I bought some pans from
www.kingarthurflour.com to make homemade muffins, subs, hamburger buns, etc. and Pampered Chef items for mini muffins and those sandwich cutters.
* start a collection of kid friendly recipes - You can find cookbooks or online sources to make things such as homemade pizza pockets, calzone, mini muffins that kids like such as pizza muffins or egg and sausage muffins. I rely on my Taste of Home cookbooks and online sources.
Some basic guidelines:
* know what they like to eat - their likes/dislikes, and, of course, consider their allergies etc
* keep cold foods cold and hot foods hot
* make it look appetizing, colorful, and fun
* the kids can help make their lunch or at least one of the components
* it's nice to add a note or something special
HTH*
taco bell, starbuck's, etc. I would let her purchase lunch more often if they had healthier selections. 
I agree completely. 
Sometimes I wish they'd buy now and then for variety though. Plus our schools have done away with regular milk in favor of this NASTY looney tunes milk. It has a longer shelf life, is cheaper for the school to buy and store, and comes in different flavors (banana, strawberry, etc). Most kids think it's NASTY tasting and I don't want my kids drinking milk with a longer shelf life 
What a great thread, I am getting so many ideas. Sometimes I give my daughter the little rice cakes and fruit and yogourt, sometimes salad and pizza rolls in a hot thermos of course, sometimes peanut butter and banana sandwhiches cut into triangles with chips. I find the odder the meal and the different shapes appeal to her more... 
