I always do some sort of baked oatmeal...since it's just me I'll do up a 8x8 pan and then cut up into 6 pieces and freeze. I'll have 3-5 different varieties in the freezer at any given time. Or I'll do them in muffin tins. Blueberry/maple, strawberry, chocolate chip (just a few minis!), banana coconut, pumpkin, apple.
Easy breezy - take out the night before and put in a container and grab on the way out the door for work. Nuke at work. Sometimes I'll add a little milk, but usually it's "as is" and very moist, high fiber, low fat, yumminess.