Dr. BBQ's Big Time sweet rub recipe is a winner - I add more chili powder and brown sugar to it for ribs - then pulse it in a spice grinder.
I'll second the Plowboy's Yardbird for a commercial rub, mix it 1/2 and 1/2 with brown sugar and try it on ribs or chicken, you'll be glad you did. We like it on hot buttered popcorn too!