Frozen onigiri for packed lunches
Surprisingly, you can actually prepare onigiri (rice balls) in advance and stash them in the freezer. The trick is to use very fresh rice (that's moist and hasn't been sitting in the rice cooker for hours), wrap each onigiri individually before freezing, and when you take them out of the freezer -- heat them in the microwave until they're warm and soft again. If you thaw them on the counter or in the refrigerator the texture will be hard and nasty, so the microwave step is very important.
In this photo I put all of the freshly frozen onigiri (shaped in molds) in a labelled freezer bag and then sucked all of the air out of the bag with a straw before sealing (think do-it-yourself FoodSaver vacuum packing). This helps ward off freezer burn.