I might suggest that there are some rare breeds that are newly developed but not in the hands of many as of yet. It seems that this will change over time as there is great interest in them. In addition to the Maiden Rock mentioned by Dan Powell, most are probably aware of the Buff Laced Brahma large fowl that Dan has spent years developing. Big Medicine has also spent many years in the development of Silver Laced Brahma large fowl. They both have, I think, flocks of Gold Laced Brahma that are results of their breeding projects.