The track rod runs across the vehicle behind the axle, the drag link and damper in front of it.
The steering guards from the likes of Servicetune will protect the drag link and damper, and will also have the effect of acting as a skid for the front of the vehicle, helping to avoid getting snagged up. I would say they are a wothwhile addition.
The track rod is very vulnerable on the coil-sprung vehicles, and does have a tendency to get hooked up on things too. There are a number of various protection systems for this :
1) Anti-Bend Protection : These consist of a piece of metal (normally attached to the diff or part of a diff protector) which sits behind the track rod. It won't stop it from being damaged, but will stop it from bending too far and completely messing up your traction. There is a genuine Land Rover part which works like this.
2) Complete Protection : Companies (like Southdown for example) make a guard which is essentially a large piece of box steel that is bolted onto the axle. The track rod is passed through the centre of this and is hence very well protected.
3) Adding Strength : The track rod is replaced with a much stronger item, or has a strengthening sleeve slid over the top. This has the effect of making it much harder to damage the track rod.
On my 90, I went for option 3. Since in my view it is better to have a strong track rod which won't bend in the first place. I have seen on many occasions track rod damage caused by forces acting on the wheels and not directly on the track rod. (for example wheels in ruts, etc)
Hope this helps.