This is what I use.
1/2 cup dark brown sugar
1/4 cup paprika (Sweet Hungarian Paprika if you can find it)
1 tablespoon fresh ground black pepper
1 tablespoon sea salt
1 tablespoon chili powder
1 tablespoon garlic powder
(I use McCormick California blend or granulated)
1 tablespoon granulated onion
(I have used McCormick california blend powder)
1 teaspoon ground cayenne pepper
1/2 tsp ginger
2 tablespoon raw sugar
PREPARATION:
If you use granulated products, you will have to grind them. I use a coffee grinder.
Combine all ingredients together, using a wisk and transfer to an air tight container.
I don't dry my brown sugar like in John's recipe below, but I did dry it when I made his to see if it made a difference. I've not had a problem with any clumping when I made my rub, just keep it air tight!
Here's one from John.
http://www.patiodaddiobbq.com/2009/02/all-purpose-bbq-seasoning.html