I have made my own rubs, bought rubs from barbecue places, ordered rubs from websites, but I have to agree with ShadowNick above, Emeril's Rib Rub is really very outstanding. I use it more often than anything else. I will still make my own if I am after something a little hotter, but its hard to beat Emerils. Maybe I am a philistine for saying that??
I am curious as to the comment that the Medium is the red headed step child of the BGE line. I have an XL, have had it for 5 or 6 years. I bought a Medium now that its just the two of us at home. I use it more often that my XL now and really like it.