About a year ago I watched Bobby Flay on Food Network doing a piece about La Caja China, also known affectionately as a Cajun Microwave or Redneck Microwave. It's used to roast pigs.
This "microwave" is a wooden box lined with metal flashing. The pig (or other meat) is placed inside the box, the lid is attached, and charcoal is placed on top of the lid to roast the meat inside. The grease flows out the bottom into a catch pan. It's simple, but very effective.
Using this method, you can roast a pig in less than 4 hours. It's very popular for family reunions, taitgating, graduations, Luau's and anytime you need to feed a lot of people. It's seems very simple to use and is priced affordably.
The Cajun Microwave is a similar pig roaster. Here's an excerpt from CrawfishGuy.com that describes the cooking method in more detail:
All grease drips towards one end of the box and out through two holes in the floor (use a catch pan to eliminate any mess). The floor can be lined with heavy duty tin foil before each use (minimizing the cleaning needed). If the box does get grease on it, simply wash out with hot soapy water and let dry.
If you're a do-it-yourselfer, here's a CD ROM with instructions for building a Cajun Microwave. This web site have a nice picture of the inside of the box.
There's more than one way to cook a pig, and definitely more than one way to make a pig roaster. Stay tuned for my own pig roasting project later this year.