I always do a mixed fruit, meat and cheese display. Depending on how sophisticated the pallets of the guests are...you can do the normal cheddar, monterey jack, etc or you can go upscale with brie, camembert, chevre, etc. I take some Italian sausauge salami and cut it up as well. I make a beautiful tiered display using fruit, sausage, crackers and wine bottles.
Another easy appetizer is a modification of the chili-cream cheese. I take a can of crab meat and mix it with cocktail sauce and lemon juice. Take this mixture and put it all over a large block of creamcheese with a hole in the center. Place this on a dish with lettuce and put shrimp and lemon wedges all around the perimeter of the block. Fill the hole in the cream cheese block with cocktail sauce. Place a dish of different type crackers next to this and you have a great display.
Both these can be done way beforehand.
Another thing I've done is a mashed potato bar. Take mashed potatoes in a big bowl surrounded by all kinds of toppings: sour cream, chives, cheese, bacon, steamed vegetables, etc. Much of this can be done way ahead of time. If you have extra wine or martini glasses its a nice touch to put these out for people to make their tatotinis!!!
Can you guess that I'm an event planner....I have hundreds of ideas...let me know if you need any more!!