My current travels to Seattle made me think of this one; what's the best beer you've had at an airport? (And which airport was it?)
Chicago O'hare now has a little Goose Island beer stand (Right next to the "Col O'hare" plane, if you want to ask someone there where it is), that's probably the best I've found at an airport.
[Edit] They carry 5 or 6 different Goose Island beers; which is quite impressive for an airport stand.
Brussels and Amsterdam Schipol have some great beers available in duty free (or the little food shop outside the secure area in Amsterdam), but I don't remember anything worth writing about within the terminal or that you could drink there....
Adam