Open letter to rat4 about introducing anonymous transactions using Ring Signature
(DarkCoin wants to start working on it after open sourcing their DarkSend CoinJoin mixing, rat4 could still be quicker to implement it...):

BlackCoin the first PoS-only Coin with Ring Signature for anonymous transactions
http://www.reddit.com/r/blackcoin/comments/25rg4w/blackcoin_the_first_posonly_coin_with_ring/

That would be fantastic and would let BlackCoin skyrocket... PoS only and Ring signature mixing would be unbeatable!!!