Somebody asked about it in another thread, so I'll post the recipe here.
This is the rub from The Salt Link BBQ restaurant in Driftwood Texas.
I found that it works great on pork butts (provides just the right amount of heat), so I searched around and found a clone for it.
1 part Kosher Salt
1 part Black Pepper
1/3rd part Garlic Powder
1/3rd part Cayenne Pepper
Mix well. (and keep it out of your eyes - don't ask me how I know that
)
I usually make a huge container of it and keep it in the freezer..
The commercial version is a little more powerful, but I've settled on the 1/3rd part Cayenne to tone it down a notch.