I roast my grains in a skillet, stirring constantly with a spatula. I've taken millet pretty gosh-darn dark that way, but can't comment yet on the flavor as I'm still wafting it to mellow it out. Although I wonder if that's necessary, as the lack of a husk should hypothetically prevent much of the harshness and astringency that people complain about with roasted barley. I did a black IPA with sprouted quinoa that I roasted that way, though, and it came out nice and chocolatey. Of course, I also used a little bit of candi syrup to help along the color...I don't seem to be able to get the grains to contribute a significant amount of color, even when I roast them suuuuuper dark. Heck, I full-on carbonized some buckwheat the other night (got distracted during the roast by my roommate's puppy, and stopped stirring it at the very end), and just for giggles I steeped some of it for a while before throwing it out, and only got a very light brown color off it. I just don't know what I gotta do to get a nice black color without resorting to candi syrup, burnt honey, or molasses!