The best rub...
1/2c Dark Brown Sugar
3 T coarse salt
1/2 T fresh ground pepper
1 T chili powder
1/2 t cayenne (omit for "mild")
1 t old bay seasoning
1/2 t ground thyme
1 T onion powder
1/2 T garlic powder
Feel free to adjust this to your liking, I like the rub to complement the meat, not overpower it. This might not be as LOUD as some of the rubs out there.
Ribs should be completely dry when applied, and left to set until they reach room temp WITH the rub on...then smoke slow and low. Then right before they're done, slap on that sweet baby rays and put a little more heat on them. I'd go on my gas grill, and sprinkle a little extra brown sugar on at this time too.