I've been lurking on this board for a while gathering info. My wife and I plan to buy an xterra in the next year or so, so i've been gathering info. I currently have an '87 Toyota 4runner and frequent some toyota boards with great information. Recently some tech has come out on crosslinked front air shocks that I thought might also be applicable here. I don't know if this has been discussed before, but the basic idea is to plumb the front shocks together to make the ifs act similar to a solid axle in that when one wheel is flexed, the air goes into the other shock giving an articulation effect. Here's an article that may be of interest:
http://www.4x4wire.com/toyota/tech/air_shocks/

Not 100% sure it would work on an x, but I figured I'd share anyways.