I would definitely go savoury, as I get dissappointed when most of my friends bring sweets

I make a...
zucchini slice and slice into bite sizes pieces
bacon and egg pastries, just cut a pastry sheet into 9 squares, pop into a miffin or cupcake tins, fill with a mix of bacon, egg, cheese, mushsoom, tomato (what ever really) and bake in a hot oven
Zucchini, fetta and corn fritters, with a yogurt and mint dipping sauce
Home made sausage rolls
or if I am being a bit more fancy
Pastry cups, filled with caramelised onion and camenbert cheess or brie and bake in the oven until the cheese is melted, you can also grill chicken and add to them... sooo good