I took the Pennywhistle Book of School Lunches,(titiel is something like that) out of the library last summer to give me some inspiration. I also got some of those little cold packs that I slip into the bottom of her lunch box; they keep things cold enough for safety (they're still pretty cold when she gets home). I also bought a wide mouth thermos and small plastic containers that hold maybe 3-4 ounces of food.
Anyway, what I got out of the book is that I try to give her small helpings of a variety of things--some protein, some grains, some fruit and veggies. So, for example, today she went with blueberries, whole grain tortilla chips, a thermos with Annie's All-Stars (spaghetti), a Vruit Juice box, and a buttercotch krimpet tastykake (I'm not THAT much of a whole foods purist, tho' i try).
In the beginning, I actually used menus from the books, but I soon learned what got eaten and what didn't. Some other ideas:
crackers and cheese
small sandwiches--I use cookie cutters sometimes to make them fun--hearts for Valentine's day, moons and stars (her favs) other times.
she's a vegetarian, so i go for cheese and pickles, cucumber sandwiches, pb and j.
carrot and celery sticks (sometimes with dressing to dip)
ants on a log (celery sticks w/ pb and raisins)
I've tried different breads which I know works for other people, but we are less successful with that--you know, like pita, or tortillas or bagels
soups--unchicken noodle, minestrone, lentil are her favs
small fruits, whether apples or oranges already sliced, or berries or grapes
yogurt, or drinkable yogurt
sometimes I'll wrap some leftover tofu nuggets in aluminum foil and slip them in the already warmed thermos, give her her dipping sauce in a little container; same thing with hand held quesadillas. We make them in the microwave--wrap a whole wheat tortilla around the cheese and then cut it in half and stuff it into her thermos. Add a little salsa in a container.
Hope these ideas give you some inspiration.