While school bags are common to all age groups, lunch packs aren't very well received at the middle and high school levels. Buying lunch is a popular option, but carrying lunch is more cost effective for many families weathering an economic storm. Brown lunch bags are an obvious solution, but there are also many simple, insulated lunch bags available now. The nice thing is that this removes the stigma associated with a lunch box, as a lunch bag is pretty low key. You can find a wide range of insulated lunch bags here, ranging from simple solids, to decorative designs.
If you are looking for coordinating school bags for girls, with matching lunch packs, read here.