BUT THAT SITE IS AWESOME
The Skepticle aquarist happens to be one of my favorites as well, because as the name inplies they seem to question evey claim and prove/disprove things with good science.
Any salt that is NaCl will work. Either buy the Aquarium salt from the fish store or just use any food grade table salt that is NaCl (and not KCl).
As said any NaCl will work. I use Mortons Iodized salt because that is what was in the house. If you are going to go buy something, get the non-Iodized salt simply because you don't need the Iodide, not that it will hurt anything. Freshwater aquarium salt works as well, but usually costs much more. the only thing to watch are marine salt mixes which contain a lot of stuff other than salt.