sandwiches
cheese cubes/sticks
fresh fruit
raw veggies
raisins
muffins
trail mix (you can make your own)
cold pasta salads (you can add in assorted proteins)
http://www.fit-fresh.com/landing_kids.php
http://www.fit-fresh.com/products/transportation/
I'm such a fan of these containers. The removable ice packs keep things cold.
If you don't like the removable ice packs, these are pretty great too:
http://www.easylunchboxes.com/