Healthy Child, Healthy Planet recently posted this list of 20 Creative Ideas for Healthy School Lunches. Most of them are not vegetarian, but it's always helpful to have options for those who do include meat in their diets.
Another nice lunch blog is the Laptop Lunchbox site. They post a weekly menu with easy ideas for busy parents - again, they are looking to sell a product (albeit a very good one, I can vouch for them!) but the ideas are great and it's easy to make your own bento-style lunch without the fancy "Lunchbox System".
Speaking of bento boxes, there was a great article in the latest issue of Mothering magazine full of beautiful, if somewhat over the top, mealtime creations. Another source for bento ideas is the Foodie Footsteps blog - subtitled Adventures in Bento Lunches for My Little Foodie. Not all vegetarian, but definitely more do-able than some of the boxes in the Mothering spread. Check it out!