Master T started Kindy last year, i only had to make lunch 5 days a fortnight. I generally stuck to choose one item from each of these categories - main, fruit, dairy with sweet & savoury snack. Morning tea we were asked to bring a piece of fruit for the class to share.
Here are some links to some fantastic lunchbox ideas for bento style lunches. I dont always make my fancy with the cute cutters you can get. If you live near a Daiso apparently you can get lots of great goodies for only $2.80. We dont have Daiso in WA so i got mine mostly from ebay and Little Bento World