In addition to Vegan Lunchbox (which is great) I also recommend Lunch In a Box. Great preschool lunch blog.
AFA tips for lunches, before I list options my first suggestion is to pack the night before. Everything goes much better & the kids eat healthier when I pack at night. I just do it while I'm cooking dinner since I'm in the kitchen anyway.
Now, what to pack. My DD loves it when I pack her a salad for school lunch. I put lettuce, cheese, broccoli, lunch meat, whatever I can find, in the salad & then do the dressing seperately. She always loves it & its actually pretty easy. DS loves for me to do meat & cheese kabobs as well as fruit kabobs. I bought a ton of little skewers (about as long as a sharpened pencil without the eraser thing) & I use them a lot.