My two favorite uses for the hanging rack:
2. Chicken halves, smoked by their own juices. The dark meat gets more heat since it's closer to the fire, and it protects the white meat and keeps it from drying out.
1. Smoking peppers. All summer, I beg the fine folks at the farmer's market for ripe (red) poblanos and jalepenos. When they come through, I tie them up on strings, hang them over a ceramic heat sink, and build a snake of lump to make a low <200 fire for 36-48 hours. Then I have ancho and chipotle chili to get me through the winter (and spring, and summer).
I've also done whole fish and ribs and turkey breast and leg of lamb, but these two are the highlights.