Many of the meals I've seen so far are full of exotic vegetables and sushi, but there are also tons of pictures of kid-friendly meals, like the one below. (Photo found on Photobucket, I don't know who took it.) My 4 year-old daughter would just love this!
From what I can tell, Bento is basically a very creative Japanese way of packing lunches in tiny containers and compartments. There are special Bento containers, but you can also do it using simple (frugal) things like cupcake papers.
What is Bento?http://www.airandangels.com/bentobox/intro.html
Bento photos on Flickrhttp://www.flickr.com/groups/bentoboxes/pool/
This one includes some cute kids' themed lunches:http://mmmbento.livejournal.com/
Bento Yum: http://www.bentoyum.com/