Do you have Super Clients?

Over at Brand Autopsy, John Moore published excerpts  of a Wall Street Journal interview with Greg Brenneman, CEO of Burger King.  Here was the quote from Brenneman that caught my eye:

WSJ: Speaking of indulgent, you call your best repeat customers "Super Fans" -- the 18-to-34-year-old males who come in three to four times a week. How are you strengthening efforts to appeal to them?

Brenneman: If you think about what drives our business, "Super Fans" are something like 25% of our customer base, but 50% of spending. If we just get one more visit out of the Super Fan, it's like a 10% increase in comparable sales. It's about understanding who the core consumers are and getting the kind of indulgent products they want. You can't be everything to everybody. If you look at the Enormous Omelet Sandwich, we didn't beat around the bush with the name. It's an indulgent breakfast sandwich, and it's absolutely geared at the Super Fan.

Who are your Super Clients?  What percentage of your revenues do they contribute?  Do you even know?