I've been using my toaster oven a lot too (use the regular oven in the evening when it is cooler). I made meatballs, and baked hamburger buns in it. And, I confess, corn dogs, but that doesn't count as cooking. I guess I could even plug it in outside to keep the heat down.
I've heard you can cook chocolate chip cookies in a hot car (takes a while) but I haven't ever tried it.
For hot days I like sub sandwiches, pasta or taco salad.