A good set of tires, poly bushings, a lowering kit, beefier sway bars, (ours are pretty stout, but I think that the Bronco ones are bigger than ours, and I think that hotchkis makes some for our application) poly body mounts, shave weight off if you can... Hmmm... That's all I can think of off my head, but I'd also recommend upgrading the brakes.
Another thing that I'm probably going to try in the near future is a watts linkage on the rear end, because I've managed to bend my rear leaf springs a little from the hard corners, so I'm definitely getting some flex there. Hopefully that will make a difference, but I won't be able to say for sure until I've tried it.