While the early Facebook widgets have been fairly primitive, some of the more recent offerings are showing promise. No, I'm not talking about Pirates vs. Ninjas. A simple widget that I just installed is Friend Wheel.
Friend Wheel creates a simple visual map of the relationships between your friends. There's even an interactive (flash) version that lets you drag and drop elements around the screen. The map looks remarkably like the type of visual maps that we provided to the intelligence community during my ClearForest days. Of course, none of the people in my map would be showing up in their maps (I'd hope).
You can grab the Friend Wheel widget here.