I'm still tweaking the design on mine, but so far I'm pretty happy with it. It is as simple as you can get - 2 T shaped stands that bolt together and support a spit made from 1" steel pipe:

I try to go for a roast pig vs. a BBQ'ed pig - i.e. I want the loins cooked to 130-150 and the ham and shoulders cooked to 180+, I don't have any coals in the center, and cover the ends of the pig with a foil tent to hold in more heat. I take the center foil out for a lot of the cook. I'm planning on replacing the foil with 6 sheet metal doors, 3 on each side. If anyone has anything made out of sheet metal (old file cabinets, appliances, etc.) let me know - I'll be glad to take them off your hands!

At the end I crisp up the skin through the judicious use of a weedburner, which not only produces a great skin it also provides a great spectacle!

I've used a variety of stands for charcoal grates, but I built it low enough so that you could just build the fire on the ground and use rakes to move the coals as needed. The whole process is fairly labor intensive, but it works well. Let me know if you're interested in borrowing it or if you have any questions.