So the list so far:
Rare Dankness (www.raredankness.com)
303 Seeds (www.303seeds.com)
Centennial Seeds (www.centennialseeds.com)
La Plata Labs (www.laplatalabs.com)
Reserva Privada (www.reservaprivadacolorado.com/)
Cannarado (www.cannaradoseedco.com)
Rootseller (www.rootseller.co)
The Bank (www.thebankgenetics.com)
BOG Seeds available at Growfax (SooperSmurph)
other Colorado seed companies:
The Chosen Few Seed Co. (facebook)
Johnston's Genetics (facebook, 'tude)
Down With Dirt (facebook)
14er Holistics (Boulder, not denver)
Haven't heard of them here yet... Colorado Seed Bank thread: