[Steve L]

Blue Mountain Brewery makes 'Kolsch 151' and it's quite good. Unfortunately it's only available in Virginia, DC, Maryland, North Carolina, Michigan, Pennsylvania, New Jersey, New York, Ohio and West Virginia. The only one I know of other than those already mentioned.

[chumley]

Having spent three days in Cologne this past October I did extensive research on this subject. 

The best one was Päffgen.  it had a nice straw/mowed grass crisp bite to it.  Wonderful stuff.

I also greatly enjoyed Fruh, Mühlen and Sion. Mühlen had the best fresh malt flavor.

Gansel, Peters and Gaffel were also quite nice.

Probably the only one that didn't do much for me was Gilden.  Kind of like the Coors of Kolsch.

[Iliff Ave]

Having spent three days in Cologne this past October I did extensive research on this subject. 

The best one was Päffgen.  it had a nice straw/mowed grass crisp bite to it.  Wonderful stuff.

I also greatly enjoyed Fruh, Mühlen and Sion. Mühlen had the best fresh malt flavor.

Gansel, Peters and Gaffel were also quite nice.

Probably the only one that didn't do much for me was Gilden.  Kind of like the Coors of Kolsch.

Coorlsch! Seems like most of those might be hard to come by in CO