This is a great way to reduce the volume of your massive tomato harvest for storage! I buy lots of incredible heirloom tomatoes from Wild Boar Farms* each summer, and roast them to remove water (heirloom tomatoes are VERY wet) and concentrate their flavor. Then they go into the chest freezer for off-season use in other dishes.
*Like the look of the tomatoes you see in these pictures? You can buy seeds online at the Wild Boar Farms website. If you grow tomatoes, I can't recommend their stock highly enough.
Step 1: Prepare tomatoes
Chop small tomatoes in half, and slice larger tomatoes in thirds or quarters. Lightly coat your baking dish in oil; I use spray canola for this part because I'm lazy and these heirloom tomatoes carry so much liquid they don't need more oil on the bottom.
Place your tomatoes in a single layer in the baking dish, then drizzle with extra virgin olive oil. Sprinkle with salt, pepper, and spices; here I used chopped fresh rosemary and dried oregano. Optional: stick garlic cloves in any remaining spaces to roast and do some serious flavor-trading.
Important storage notes: refrigeration kills off proper tomato flavor. Keep them on your counter, and check daily for softness or incipient mold. Don't wash them until you're ready to use them.