Would be sweet to get altcoin trading on Polo going - looks like the work is done already.
Its definitely on our radar. At the moment we are working on stabilizing our platform. We have moved few of our background services to new provider, so we are more focused on that for now.
Poloniex is another one that many have requested including ok-coin.
And huobi... and OKcoin futures... and margin trading on Bitfinex... GET TO WORK!!!