Along the lines of the candy buffet, comes the decorate your own cupcake display.
This one was featured at a wedding, but the idea crosses all party lines - especially with children.
One thing to think about when planning one is the number of guests who will need to be accommodated at once. No one wants to stand in line forever just to decorate a cupcake. Using a round table like this, place a large stand or maybe even two at different heights at the center of the table. Then totally surround the table with a circle of toppings. Have two or three sets of the same toppings at the table so many more guests can be served at once.