I'll add my two cents that the current beer selection is lame. It seemed particularly lame when I was recently flying home from Germany. They used to stock some "local selections" on int'l routes: has that practice been abandoned?
Since they're now charging 5 bucks in the main cabin, you would think CO could afford to stock an "interesting" beer. As previous posters mentioned, Petes Wicked Ale and some others have made appearances in years past. And I agree that Fosters is a strange selection.
As a Texas airline, Shiner Bock would make an excellent choice. It's tasty and what I would consider "accessible" to a general beer drinking audience. They also seem to have dramatically boosted their distribution in recent years. Yuengling would be another good regional choice. And I don't see what's wrong with "mixing it up" on board. It might a bit interesting to see what was available on any given flight.
And it couldn't be worse than the current selection.