First and foremost - sliders. Go to the slider comparison thread (stickied in 4x4/offroad forum).
Protection for the rear control arm brackets (on frame rails) is a key area. See All-Pro's stuff.
Stronger rear control arms, if you do any rock crawling is necessary. See All-Pro again.
Front engine skid and tranny/t-case skids. See Bud Built Skids.
I agree. Though I wish I had known.. my rear control arm bracket passenger side has seen better days.