This is what I was able to determine so far. Apperantly there is no industry standard for shock absorber oil. Most guys seems to recommend Automatic Transmision Fluid. Some Companies does have a "Shock Absorber Oil". They all seem to have the following in common:
Synthetic Hydrocarbon with High VI: 165 to 210 Low pour point: -36 to -48 degC Viscosity: 32 to 35 cSt (for motorcycles and extreme temp. conditions this can be as low as 10 to 15 cSt)
I'm going to work with this information, unless there's anything that I've missed or something that anyone would like to add?
The antifoam, oxidation stability and seal compatibility will be adressed by using a good quality ATF oil or synthetic, high VI oil as mentioned before.
However, the damping effect will be dictaded by the oil viscosity in a similar way that response time in a hydraulic system is affected by viscosity. Too low viscosity and no damping will take place, too high viscosity and too much damping will take place. Either way, both will result in an uncomfortable ride.