I just got Mike Mills' book, Peace Love and Barbeque. There are lots of recipes in there and this rub stands out.
1/2 cup paprika
1/4 cup kosher salt, finely ground
1/4 cup sugar
2 tablespoons mustard powder
1/4 cup chili powder
1/4 ground cumin
2 tablespoons ground black pepper
1/4 cup granulated garlic, finely ground
2 tablespoons cayenne pepper
Mike grinds the course ingredients in a coffee mill dedicated to spices and stores the mixture in a tightly covered container. Keeps indefinitely but won't last long.