If meat's an option, people seem to enjoy little meatballs on a toothpick (bake 'em... faster than frying).
If you can get an in-season deal on them, grape tomatoes, or grapes, just loose on a plate, maybe with toothpicks nearby.
Or roast vegetables: bite size pieces of zucchini, eggplant, peppers, and maybe (drained) tomato pieces, all of which are in season many places. Whiz a few cloves of garlic with some oil, salt, and pepper, plus either basil or a couple of reconstituted sun-dried tomatoes, and stir the veg around in it. Roast in a single layer on pizza trays or cookie sheets until not-crunchy (ideally hot and fast, maybe in the oven with the pizza). Good either warm or room-temp. (If you do the sun-dried tomato marinade, try adding some corn on the cob cut into about one-inch lengths. A little messy to eat, but they'll-talk-about-it-afterward good!)
None of us seem to have a good dessert idea for you. But I've had good fun at parties by buying a huge watermelon and just hacking it into chunks for people.