Spritz bottles for apple juice/bourbon/etc spritzes.
Squirt bottles for homemade sauces.
A good cutting board to cut ribs on, pull pork on, slice brisket on, etc.
A long slicing knife for brisket is helpful as well.
A charcoal chimeny if you have a charcoal smoker.
And most importantly... A cooler and ice packs to send me samples.