I unfortunately don't have my chickens anymore and put a hold on my projects as I'm trying to expatriate, but before I had a flock that were a mix of Dominique, Ameraucana, Polish, and Marans. I liked the variety in egg and feather color they had so I didn't select towards certain ones, but I was selecting towards a very cold-hardy free-range bird that bred true for crests, beards, and clean feet. About half were barred, and some of the others came out with beautiful color combinations I've never seen before. After the second generation, I noticed my breeding roo and a few of his chicks had one extra toe on the left foot. Fully formed, fully functional, and always just the one foot. It didn't matter much to me as the chickens were otherwise healthy and unbothered by it. It seemed to be a dominant trait.
I'm hoping to do something very similar in the future when I have land again, with beards/muffs, crests, blue eggs, pea combs, and a variety of colors. I plan on starting with Ameraucana hens (and a fibro or two, because I like them) and breeding in the other traits through the roos, which is what I did before and it went well. Aside from those four traits I just plan on letting nature and genetic drift take its course. Ultimately I want to create a flock that's genetically diverse and healthy, evades predators well, and can tolerate very harsh winters. Of course, that's my life-long goal, I don't want to cull heavily in the first few years as I don't plan on bringing much outside blood in after I have the traits that I want and I want to avoid inbreeding depression. Here's hoping!