Answer:
There are so many things! Here's a condensed list though:
- chafing dishes (with candles and pans)
- serving utensils
- dinnerware
- silverware/flatware
- carts
- serving bowls/trays/platters
- insulated transport carriers
- party tubs
- linens
If it's going to be a big operation you might want to consider commercial kitchen equipment.
Here are my fave sites:
http://www.missionrs.com/catering-supplies.html
http://www.williams-sonoma.com/search/results.html?words=tablecloths
http://www.amazon.com/Kitchen-Table-Linens-Dining/b?ie=UTF8&node=1063916
http://www.linentablecloth.com/