I love Caprese Skewers-- Rachel Ray did a version of this once. You buy those little marinated fresh mozzarella balls and put them on short skewers with cherry tomatoes and fresh basil leaves. So simple, but so delicious.
I also love melon with prosciutto. The easiest thing to do is take 1" cubes (or balls if you have a melon baller) of honeydew or cantaloupe, wrap it with a small piece of prosciutto and stick it on a toothpick.
Deviled eggs are good too. If you want to make them seem fancier, just sprinkle some caviar on top. Or you can sprinkle them with paprika and chopped chives to make them look really festive.