This Houston Chronicle article says to start with some high-quality cheeses: aged cheddar and crumbled blue. Sure, you could grab whatever "specialty" cheese you find in your supermarket case, but come on, it's Thanksgiving. Why not go all out and get some Fiscalini Vintage Bandaged Cheddar and Maytag Blue?
In a food processor, combine the shredded or crumbled cheeses with cream cheese, sour cream, Worcestershire sauce, garlic powder, salt, and pepper. Fold in green onions, shape into a ball, and chill. Now cover in crisp cooked bacon. Don't invite your cardiologist. Suprisingly, though, if you can keep your consumption down to 1 tablespoon, you will only be taking on 165 calories and 9 grams of saturated fat.
You know you want to try this, and why not? What is Thanksgiving for but to give thanks for such Frankensteinian concoctions as the cheeseball? There's always 2008 to work off those extra cheeseball pounds.