Here are things my LO likes...
Cheese or Black Bean and Cheese Quesadilla on (smaller sized) whole wheat tortilla. I mash the black beans with a fork onto a tortilla (only onto half), cover the beans with a little mild cheddar cheese, fold the tortilla, microwave for about 30seconds, cut into little squares.
Any kind of fruit
Frozen veggies - I buy the bags of mixed veggies, there are lots of varieties. I put some in a child-sized bowl, add about 1/2in of water, microwave until warm.
Peanut butter on crackers (if he's not allergic, of course)
Frozen waffles or pancakes
I'm sure there are more, but that's all I can think of at the moment. Sometimes I'll give leftovers from the last night's dinner.