fruit salad
waldorf salad (surprisingly good!)
plain ol' salad with dressings
I'd suggest running to the produce section of your market and looking for things that are ready-made. Acme has a waldorf salad ready-made, it's good. Then they have things like salsa, pico de gallo, etc that you can put with corn chips; bakery goods, nuts.
Potato salad and macaroni salads are great but they really need to be prepared the day before. No one likes them hot.