FeatherCoin, ChinaCoin, Feather2Coin, YaCoin ... are copies of LiteCoin.
Calling YACoin a copy of LiteCoin is a bit of a stretch...
Its a copy of the original idea of litecoin isn't it? cpu only.
My understanding of Yacoin is that it's generally based off of the litecoin code, but the hash it uses requires non 1024 values, which screws it up for GPU mining, although it should be possible to develop an fpga and eventually an asic for it.