The aubergine (eggplant) has to be one of my favourite vegetables. It's so pretty, and so versatile. You can cook it lightly to retain a bit of firmness, or reduce it entirely to a mash to enrich and thicken soups and stews. Its only drawback is its tendency to soak up dramatic quantities of oil when sauteed on its own; you can get around this to some extent by marinading it in something salty (a soy-sauce based marinade, for example) before sauteeing it. The salt disrupts the cells of the vegetable, and makes it less able to absorb oil.
Or, of course, you can cook it with no added oil at all!