In a small bowl, whisk together the balsamic vinegar, olive oil, honey, oregano, garlic powder, salt and pepper.
Place the eggplant slices on the grill and brush with the balsamic mixture. Grill for about 4 minutes, then flip and brush with more of the balsamic mixture. Grill for an additional 4 minutes, or until the eggplant is tender and lightly charred.
Serve the grilled eggplant with the remaining balsamic mixture.